From the Microsoft post:
Facebook has made an update to their Graph API that will impact Microsoft apps and services. Facebook’s Graph API is the tool that we use to connect your Microsoft account to Facebook. It brings contact information from your Facebook friends into Outlook.com and the Windows People app, keeps those contacts up-to-date, and provides options in apps and services like Photo Gallery, Movie Maker, and OneDrive.com to share to Facebook. We collectively refer to these features as Facebook Connect.
Due to these changes, Facebook Connect features will no longer be supported. This article explains how these changes will impact your connected apps and services.
Outlook.com and Microsoft Contacts
If you’re a new user, you won’t be able to connect your Facebook contacts to your Outlook.com account.
If you’ve previously connected your Facebook account to Outlook.com, your Facebook contacts will no longer be updated with information from Facebook.
Those are the general account impact, across desktop, web, etc. Turning its attention to how Facebook's changes affect older versions of Windows Phone (pre 8.1):
Windows Phone 7 and 8 People app
The People app newsfeed data will no longer be updated with data from Facebook. Facebook contacts and Facebook events in the Calendar app will no longer be updated with information from Facebook.
Windows Phone 7 and 8 OneDrive
Posting a picture or video to your Facebook wall or Facebook profile on Windows Phone 7.5/8 and Office will no longer work. As a workaround, post photos and videos via the Facebook website or Facebook app.
Windows Phone 7 and 8 Photos
Posting a photo or video to your Facebook wall or Facebook profile on Windows Phone 7 and 8 will no longer work. Also the integration of your Facebook photo into your Photo Gallery will no longer work.
As a workaround, post and view photos and videos via the Facebook website or Facebook app.
As the 'workarounds' mentioned above suggest, the obvious way to 'do' Facebook is via the dedicated application in the Store, and this is guaranteed to still work, of course. It's regularly updated too.
On current Windows Phone versions (8.1 and above), the installation of the Facebook application onto a device does 'unlock' Facebook integration into the OS (e.g. appearing in the account set-up section of Settings) and the People application.
In short, don't panic, all of this is unlikely to have any impact on anyone reading this on AAWP, at least at the phone level. The main thing to perhaps note is the split between Outlook/Microsoft and Facebook at the top level. Here's hoping that the two companies don't drift apart completely at the ecosystem level...