If a Kinect-like thing is really going to succeed, it has to be in every console, which I'm assuming will be the case with the next Xbox, at least. Voice commands would be pretty cool, assuming they always work as expected.
Graphical improvements would be good, but even with this gen, graphics are pretty hot already. I mean, there's room for improvement, sure, but let's get focused on stories and stuff again.
And, let's try and keep the hardware issues to a minimum this time around, ok Microsoft?