I really don't believe this at all.
It is going to help the Xbox 360, but there will probably be more titles for the PS3 motion tech already, and there will certaintly be more Wii motion tech titles available.
They should be positioning the 360 Natal pairing as cheap, uber-easy to use HD motion tech gaming. But its not going to be the equivalent of a new launch.
I don't think that's quite the point they're making here. This is more about how the launch of the peripheral will be APPROACHED. They are going to approach retail release and marketing as if it were a new console launch. Therefore they will look to secure quality titles and experiences that reach out to core, casual and new gamers. The PS3 motion controller+camera and Wii Motion+ will have their games and most likely familiar experiences while this will have the sparkle of "the new".
Pachter (and others) said that this tech isn't near as expensive as people think and would expect if released today it would cost between $50-100 (here is a link to where he states this: http://www.gametrailers.com/episode/bonusround/305?ch=3 ). In a years time, that should drop even more. Bundle this with the right game and integrate it into the dashboard experience and it could do really well. This would also be right timing for another significant price drop for the console as well.
For the record, I would never, EVER question the Xbox divisions ability to market something. And based on the media response already and crowd reactions from public displays of the tech, the marketing for this won't be very difficult. Just the games.