What truly makes a console next gen?

[The Fury]

It should be neither. It should just be when the next set of consoles is launched.

But I like your thinking, the idea that in previous years it has always been a large graphical increase. The increase this time might not be as noticable so interaction is the new key but that's just interaction in a game and that can be launched at any time, whether it's Singstar, Eyetoy or Kinect.

@Kantor
Kinect isn't a console in itself so wouldn't count as the new generation anyway, surely.