Post the final OS update, we're in an odd phase of the OS, where most of the stuff that ever works still works (and is supported), but things are definitely now falling off the edges, as it were. Which means that it's hard to keep track of it all - hence the table below, which I'll keep updated every so often.
Note that some dates are approximate, since even we at AAWP can't see into the future with certainty! I've colour coded table cells, with pale red for 'on the way out, with workarounds and caveats', through increasingly dark shades, and red for 'no hope!'...
|Security updates||The last update - January 2020 - has now happened for the newest 1709 branch. Theoretically, the OS is vulnerable after this, though in practice Windows 10 Mobile is now battle hardened and also a miniscule target for attackers, so the lack of updates won't actually be an issue. I'd suggest that lack of support also means that people at Microsoft won't be testing services against Windows 10 Mobile any more, but we all know that they haven't been doing this for some time, sadly.|
If something goes horribly wrong and you need a fresh start then there are a couple of PC-based utilities to help out (WDRT, OTC Updater), though they rely on the original phone 'images' being still available on Microsoft's servers. I can't imagine the download bandwidth here amounts to much, but Microsoft will, at some point, shut down these servers, probably because things are changing server-side to accommodate new services and platforms. No end date is known, I'd guess, 2021 or beyond. They're all still working right now, in May 2020, though I've had some reports on over-the-air updates being flaky for older phones. I'll report back as needed.
If all else fails, sites like lumiafirmware.com appear to have archived all the device images from Microsoft's servers. Actually flashing them on isn't trivial, so I'll save a tutorial for when the official utilities break!
|Web browsing (Edge)||Edge remains a competent browser for most sites, plus it syncs your history and favourites in the usual way. But its development stopped as of Windows 10 branch 1703 over two years ago, effectively, since the 1709 branch's Edge wasn't fully rounded out (in terms of service worker and other background operation). Which makes it something of a dead end if you're looking for more. Third party browsers like Monument Browser do more, though ultimately have the same underlying restrictions for PWAs and some other HTML5-reliant sites. Roughly half the PWAs out there work, roughly half don't - see the Flow column on AAWP for recommendations of the former!|
|Auto-backups||Until 'March 2020', i.e. over three months ago! Clearly someone at Microsoft has forgotten to turn this service off, which is handy. It's not clear whether manual backups will be possible after auto-backups do eventually finish. Watch this space - as of today, 4th June 2020, auto and manual backups are both still working just fine. I'll keep you posted!|
|Restoring from backups||Until 'March 2021' - after this, if you hard reset a Windows 10 Mobile phone then you'd have to rebuild it manually, installing from the Store, etc. Which will still hopefully function.|
|Store apps||Application updates and installs should be fine until at least the end of 2021. The old 8.1 Store was given 30 months after end of support for the OS itself, if we extrapolate that to Windows 10 Mobile then the Store might last until summer 2022. But I think the end might come the previous Christmas.|
|Store client||Ignore scare stories about the Store client itself not being updated anymore - updates with bug fixes and security tweaks will continue for at least a year, possibly more, albeit with new features and UI fanciments only for Redstone 3 and above (i.e. on Desktop/Hololens, etc.) And yes, some of these updates will have knock on effects for Windows 10 Mobile - we had problems with the Store needing a manual 'Refresh' recently - these got resolved, thankfully. But expect further small glitches going forward.|
|Auto-Photos upload to OneDrive||Until December 2020 - after that you'd have to upload images manually. It's worth noting that the OneDrive client on iOS and Android is excellent - if you do switch at some point then you essentially carry on with the same interface, auto-backup, and photo stream in the cloud (subject to your storage plan, e.g. 1TB with Office 365)|
|OneDrive music streaming||Stopped from May 2019 onwards, at least from within Groove Music app. You can still stream from OneDrive or download from both first and third party applications though - see the linked article for suggestions.|
|OneDrive||No cessation date for Windows 10 Mobile access announced, likely 2022 or way beyond - Microsoft is a cloud company in many ways now and OneDrive is central to its vision.|
|Office Lens||This being a cloud-centric OCR solution, it's utterly dependent on Microsoft allowing server access. Having said that, it's also heavily OneDrive-centric, so I'm hoping that will carry on working into 2022 too.|
|Outlook Mail, Calendar
||No cessation date announced, likely 2022 or beyond. Outlook app development is all on newer Windows 10 branches though, so the current one on Windows 10 Mobile is only receiving small bug fixes and none of the sexier stuff you'll read about in the news.|
|Office UWP applications||Updates for these will stop in 'January 2021', though the applications will carry on working indefinitely. The lack of updates is moot though, since main app development is all on newer Windows 10 branches, so the current Office UWP apps on Windows 10 Mobile have only been receiving bug fixes (at best).|
|Maps/Navigation||No cessation date announced, likely 2022 or beyond. 'Automatically update maps' seems to still work as at June 2020, but you can also 'check for updates' and pick up new maps manually, in 'Settings/Apps/Offline maps'. Do note that Microsoft is switching away from HERE Maps as a source and is using TomTom maps from now on, on the desktop and on the web, so I suspect that updates will dry up very soon.|
|News, Weather||No cessation date announced, likely 2022 or beyond. Functionality for the UWP apps under Windows 10 Mobile has been frozen for a while, but News in particular is still getting tweaks to encompass new news sources and options.|
|Microsoft To-Do||No cessation date announced, but application updates have now stopped on Mobile, with new features only appearing on higher Windows 10 branch numbers, for the Desktop. Compatibility with base (textual) To-do data is likely until at least 2021 though.|
|Cortana||This has now been announced as ended, including on Android, by the way, so it's not just W10M suffering. The search control in W10M will still bring up... something, depending on region. Probably local and Bing searching. But Cortana as an 'assistant' is effectively dead for consumers.|
|Films & TV||(aka 'Movies & TV') No cessation date announced, but several rumours. Clever money has new purchases stopping soon and no access to past purchases stopping later in 2020. Just a guess. I've checked and past purchases are still available in May 2020, the DRM still works, plus purchases can still be made, albeit through a Store app redirect, and with no warning messages in-app. Watch this space.|
|Skype||No cessation date announced for the UWP app (the Desktop is now back to Win32, effectively), but it's 100% online and requires server integration, obviously, so I wouldn't be surprised if an end date (this year, i.e. 2020) for Skype on Windows 10 Mobile was announced soon.|
|Authenticator||In theory, this will keep working for ages if it's already set up, since it relies on tokens from the relevant sites and time-based calculations. But sites might revoke tokens and require re-authentication, so a system like this isn't guaranteed forever. It'll be OK during 2020, though note that Microsoft Authenticator does more on iOS and Android, include token syncing between signed-in devices (in theory - in my experience, this is patchy, anyway). It's just a shame that this potential sync doesn't include W10M, since the app was frozen too early in development.|
|Official client is a PWA, but works very well, apart from lack of push notifications in Edge (the usual lack of 'service workers' in the browser). Here's the latest changelog. API limitations at Twitter's end mean that there's now no fully working third party alternative (at least, one that also has access to DMs).|
|Official (Osmeta-based, derived from iOS codebase) client has now been withdrawn from the Store, and even if you have it previously installed then it crashes and burns. There are numerous Facebook 'scraping' applications and options though, and these run faster and more efficiently than the Facebook original client (go figure!)|
|Facebook Messenger||Official (Osmeta-based, derived from iOS codebase) client also now not available anymore. Good riddance, arguably, since it was bloated. The solutions linked in our article here include basic Messenger support, though.|
Official (Osmeta-based, derived from iOS codebase) client has now been withdrawn, being part of the Facebook 'empire'. There's an official Instagram PWA, but it's officially available patchily under Windows 10 Mobile, available as an upgrade through the Store only if you have the original installed. Very odd. But don't despair, as the PWA has been recently upgraded and is available to anyone as a simple URL/favourite in the Edge browser.
There are also several third party alternatives, the clear favourite of which is the quirky, often unstable, but always improving Winsta UWP (which now features notifications - of sorts!)
|The official WP8.1 client has now officially stopped working. If you need a Whatsapp replacement and don't want to switch platform then see Telegram, below.|
|Telegram||Plenty of options here, with an official WP8.1 application (still in the W10M Store) that is gradually falling into disrepair, but also an official PWA that works OK (though with no push notifications, due to Edge limitations) and a third party app, Unigram Mobile Messenger UWP, which is new and improving (after the original Unigram went off into Desktop-only realms).|
|Viber||This messaging app has a first party UWP application, but reviews have been patchy - it's not actively updated. According to readers it still works fine for messaging, voice and video though.|
|Snapchat||This has never been on Windows phones and never will be.|
|There's no official client for this, but pinterest.com in Edge seems to be a PWA and acts like an application. Plus, if you still want a native UWP application experience, there's 'Piny - Pinterest with love' UWP|
The official WP8.1 application still technically runs, but has now lost search functions and is clearly on the way out. Various third party applications are being targetted by Spotify's lawyers and have now been withdrawn, sadly. Spotimo UWP was your best bet, this is being reworked as 'Strix' and will be available shortly, hopefully for Windows 10 Mobile as well as Desktop. Watch this space.
|Netflix||The official WP8.1 application has now stopped working - I don't think Netflix intentionally pulled it, something just broke at the API level. It's possible that it's just something 'broken' that Netflix will inadvertently fix, but don't hold your breath.|
|Amazon Prime Video||Amazon has never had an official application for Windows phones, but if you're happy to fiddle a little in Edge then you can watch this on the go. It's not trivial though and is a complete pain in the proverbial compared to the slick experience in a dedicated app on other platforms.|
|Audible||The excellent Audible UWP application and Amazon's service continues to work well. I'd be surprised if it's all still working by 2021 though.|
|Deezer||There's a rather good official UWP client for this, so no need to look further. I'd expect this to work well into 2020, and possibly beyond.|
|YouTube||One of the more famous spats between Google and Microsoft, this hasn't had an official application for years, though of course it works fine in the Edge browser. I'd recommend myTube!, Perfect Tube or Awesome Tube though, all UWP applications with slick interfaces and all kept bang up to date. Hopefully. YouTube does keep changing things though, so have all three UWP apps installed and go for the one updated most recently (myTube!, as I write this).|
|BBC iPlayer||This has been browser-only for years under Windows phone and Windows 10 Mobile, but it's fine. There's the usual 'log into the BBC servers' and you're in and watching. There's no downloading of programmes for watching later though, for DRM reasons.|
|Third party UWP apps||Curated into a 'best of' list here, new applications have been drying up through 2019, with just a handful of new titles each quarter now in 2020, though the Flow column on AAWP's front page gives a good idea of which applications are still punching through with significant updates.|
Do please let me know, by email or in the comments, if there are any inaccuracies in the above table or if you have information to update it. Thanks.
Verdict and Postscript
With almost no new applications, plus the obvious omissions (tap to pay, IoT support, online banking apps) that have been there for a while now, it's hard to recommend the OS to anyone. There are certainly enough workarounds and alternative applications for most enthusiasts of the hardware, but that's not enough in a world where some iPhones and Android flagships are now arguably besting Lumias at their strong suit (imaging) and obliterating them at everything else. Certainly you can get a second hand iPhone 11 Pro for £600 or so, and a Google Pixel 2 for a mere £100, both matching or beating the Lumia 950 in terms of photos, yet with the full might of modern applications and services across the board.
One valid question might be what will happen to AAWP itself from this point on? I did have one idea. Steve H had another. Bing has now dropped AAWP because of its lack of 'https' and Google will no doubt do the same. There's precious little new to report in terms of Windows 10 Mobile, so any future content would have to have an increasingly wider net, covering other mobile OS and perhaps other Microsoft hardware (Surface Go 2, Surface Duo, and so on).
Which is all possible, but the lack of 'https' needs addressing at the server level and that's down to Rafe's time, which has been all too short in recent years. So we're at something of an impasse. Is this the end for AAS and AAWP? Hopefully not, so watch the site just in case it takes off in a different direction.
PS. Do please join the occasional guest writers if you have something to say/review/discuss, do please email me at firstname.lastname@example.org if you can help directly, and well, you know where my PayPal tip jar is...