I'm repeating what Xbox Wire and Phil have publicly said is the goal. 4 generations of compatibility and your games all come with you. I'm not on the team and am not confirming anything that hasn't already been confirmed.
Okay, thank you!
Then I don't understand what this thread is about, we've known about BC for a while now:
Xbox -> Select BC with select enhancements
X360 -> Select BC with select enhancements
XB1 -> Full BC with X1 games and with the X1X enhancement patches
In short, whatever you play on your X1X, you will play on XSX the exact same way, but you'll hit the framerate/dynamic resolution cap consistently thanks to the added power. So titles with an unlocked framerate (like KH3, for instance) will run at max fps with no developer intervention, while unpatched capped titles will run as they do now on your machine (e.g. X1 AC:Syndicate will still run at 900p)
What appears to be possible as an "auto" enhancement is HDR, though, and I look forward to seeing it in action! It's really promising
EDIT: wait, even X1 games will have a whitelist?