After Microsoft revealed a list of games that would definitely be included in the Play Anywhere service, a Windows Blog update further detailed that all future Microsoft published games would be heading to the PC through the service.
The exact line from Microsoft's Yusuf Medhi was:
"Every new title published from Microsoft Studios will support Xbox Play Anywhere and will be easily accessible in the Windows Store."
It appears as though Microsoft has stealthily gone back into that article and edited the original comment to limit the reach of Play Anywhere to the games shown off on stage during E3 2016. Microsoft didn't announce the edit they made to the Windows Blog, but it now reads:
"Every new title published from Microsoft Studios that we showed onstage at E3 this year will support Xbox Play Anywhere and will be easily accessible in the Windows Store."
The entire section between the words "Studios" and "will" is new. That takes us from having all Microsoft published games on PC via Windows 10 to having only games from E3 2016 on PC. That's quite the change… perhaps we won't see the next Halo on PC after all?