Xbox One

[Vipershark]

The reason the X1 can't run 360 games is because it's x86 based while the 360 was PowerPC based. The games are coded to entirely different architectures. The "3rd OS" being able to play 360 games is simply not an option unless they make it a super powerful emulator, which I'm pretty sure today's top-of-the-line computer rigs aren't even good enough to emulate the 360, let alone a mid-range gaming PC like the X1 is.

Like I said a few posts ago, I'm pretty sure before the system even came out they said that you'd be able to play 360 games on it if get an addon.

edit- on that note, it might be possible to run original Xbox games natively considering it had a Pentium 3, but knowing Microsoft, that's doubtful.