The challenge, of course, is to get to a build that can be used as the basis for the over the air upgrade for regular Windows Phone 8.1 users. We were expecting these upgrades to start happening this week (to the Lumia 640 etc.), but I suspect that we're now pushing things into January 2016.
Here's the blurb from Microsoft on today's Insiders update:
We have another Cumulative Update for Windows 10 Mobile Insider Preview Build 10586 which we’re releasing today to Windows Insiders in the Fast and Slow ring.
This build continues to address feedback we’ve received from Windows Insiders as well as customers using our brand new Windows 10 phones like the Lumia 950 and Lumia 950 XL. As with the previous release, this Cumulative Update continues to use the minor version for differentiating between each version – so this build will appear as 10586.36.
Windows Insiders have provided great feedback on the upgrade experience from Windows Phone 8.1. We continue to use the feedback we get from Windows Insiders to improve the upgrade experience and this update has some improvements to that experience.
Going forward, we won’t be publishing blog posts to announce new Cumulative Updates for Windows Insiders to test. Instead, we’ll publish these announcements in the Insider Hub so please check there for news. If you follow me on Twitter I’ll keep sharing news there as well.
I also want to set expectations for new builds for both PC and mobile between now and the end of 2015. This time of year many of us take the opportunity to spend time with family and take some vacation time, so the engineering team will be running at a slower pace and many of our key people who drive our flighting process will be out (including me) This means we won’t be releasing any new builds to Windows Insiders until January, for both PC and mobile.
Our editorial devices are updating as I write this (the usual spinning cogs for half an hour), comments welcome if you have particular observations.
Note that if you don't see this update (10586.36) then you probably need to go back into the 'Windows Insiders' application and approve access to the 'fast ring' again. This may involve signing in again and also restarting the phone.
The delays for the Windows 10 Mobile updates to every day users on Windows Phone 8.1 is unfortunate, but if you've been living with the W10M day to day like me then you'll know that there are lots of little annoyances which would be frustrating showstoppers to anyone not as patient and as err.... enthusiastic about the OS as us. There's no point in rolling all this out until it's 99.9% ready. 95% just isn't good enough.