The success of such a commercialised launch rests solely upon three things - the quality of Natal, the quality of at least one or more of the games designed for it at launch, and [though to a lesser extent] the publicity both receive. Natal needs at least one game of a high quality in order to appeal to people, not unlike how Halo appealed to people who purchased an Xbox. Natal also needs to be fully up to par and exciting - no red rings of death this time around please, otherwise we just won't support it.
But if both of them are up to par, then Microsoft has a powerful player on its hands. If Natal can indeed generate launch support akin to that of the 360, then a lot of profit and support is to be gained. While it's not the most innovative of moves (ultimately, they are repeating the console launch formula), it has a shot of standing out.
That said, I'm not particularly hyped about Natal right now. It's got a lot to prove, and I'm going to wait until it makes some progress in demonstrating its potential.