In a surprising find, in the latest 'Redstone' Insider builds (Fast Ring) Microsoft is evidently expanding the People app with Xbox contact integration.
The feature was brought to our attention by @woelfel who spotted the addition. In essence, Windows 10 and Windows 10 Mobile will soon have the ability to link your Xbox friends to their full contact information in your People app.
Microsoft has already begun to expand the People app, which took a massive hit in functionality from its Windows Phone 7 days. Years ago, users could link apps into the People Hub to get a birds-eye view of a contact's activity. That feature was stripped in Windows Phone 8 and 8.1.
However, the Windows 10 People app does let external apps share information, such as Facebook (beta), Skype, and the old Twitter app (ironically, the new one does yet have that feature). Now, we are getting the first signs that the old People Hub functionality may be returning.