I'm still holding my breath to see what happens next holidays.
Wii is slowly declining as software support is dwindling. Its really following a normal trail off curve. Peak year was 2008.
PS3 has received no extra boost from Move and is simply riding its shifted curve due to slower ramp up of software (over all life) and higher initial price. Peak year was 2010.
X360 is the odd ball. It was about to begin trending down, but Kinect has given it a decent boost. This coming holiday will demonstrate if this boost is short lived. X360's peak could be this year. That would be amazing for a 6 year old machine.
This gen has truly been so much different than any other. The market leader failed to gain full 3rd party support due to its hardware being so drastically different than others. The two market "losers" might actually live in the market just as long as the leader (maybe longer) due to previous mentioned 3rd party shift. Only one matched the normal growth curve of (though at an far higher level) of the typical console life span.
This gen really should be called the "disruption generation" as so many things have happened very different.
More on topic, yes, its very much possible that Kinect will cause x360 to have longer sustained life, granted that's all up to software. Right now its riding the newness of the dance game and the overall experience. It will need to continue that to be successful in the long term.
