I know all games will see the extra hardware even without a patch. Of course, it doesn't mean every game will benefit, but given the possibility of the CPU being upgraded as well a locked framerate across the board is very likely.
They are not, they are even published by Ms that doesn't even have access to the original source code. Yeah, the games are tested to hell and back but the principle is about the same, the games are running better simply because the more powerful hardware removed some of the bottlenecks from the old console.
BC on xbone, save for the few games that haven't been updated to the newer version are essentially locked framerate with vsync on at all times.
Well, it's kinda confirmed when Phil himself said that, unlike on the pro, games won't have to be patched to have access to the extra resources.
His caveat was that just because games have access to the new hardware it doesn't mean they will all render at 4k natively, and to the extent they will be improved will also vary game from game. But with the gpu jump, and the likely CPU jump too, I think it's very reasonable to expect all games being locked framerate wise.