@thx:
That will be pretty rare, pretty sure most kids get their consoles in their room or a gaming room. Most adults I know that arent just total casuals and already owning a Wii, buy their kids their own console once they get past a certain age. Sure, they will move some, as a curiousity to folks who already have a 360.... but 360 sales overall arent going to be affected. There will not be a huge surge of folks who already own a Wii scrambling to pick up the newest gimmick on the block.
Motion gaming is a nonstarter until 3d TV, the only real attraction will be "total immersion". Full body control does not have anything of real substance to offer until that time. Development on that type of thing will probably start in earnest in 8-10 years, and 15 or so years out we might start seeing meaningful software. And it will be cool. ( yes 3d tv will be here soon, but I dont predict that being widely adopted and perfected for many years either).