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.
The number of "motion-tech-titles" is not important. It is about a new experience with no controller needed. Look, the Wii had almost 0 huge games after Wii Fit / Mario Kart / Smash Brothers last year. But those games were enough to get the consoles sold... in a big way. People still buy the Wii, because of those few titles. I know, there are other interesting titles, but not a single one being as big as the 3 I mentioned.
So get Natal out with the Paint Party / Riccochet / Burnout stuff. Release Milo some time later, release the titles Rare is working on and we are fine. I am not saying those titles are as big as Wii Fit or Mario Kart, but those titles are enough to get people interested in this new technology. It won't do Wii numbers, but it will be a success. I am pretty sure. This is where MS is really good at.
MS will advertise this like THE next step.
There once was a great sig here, but it got killed.
A moment of silence would be appreciated.