If I was a dev and I a tonne of footage of my multi platform game running on an unspecified platform floating around Youtube, I'd really rather it was footage of my game looking it's best on PC than looking not so good on 360. Hence I would release the PC trailer and PC demo 1st!
Even if this doesn't effect 360 sales it will surely affect PS3 and PC sales if the game looks better on those formats.
Console player buys Crysis 2, and he starts playing....: "WTF is this ****, it doesn't look as good as the trailer I saw, FU crytek ripoff", console player sells the game.
@topic , cmon Crytek give us the demo
Or at least a release date....