Did you actually process the numbers here? That's close to 50% per xbox household with all the multiple units sold. Just for exclusivity sake the killer Kinect game would have generated sales you couldn't with normal 360 games because the market competition is a lot fiercer for normal 360 games.
So, I really don't buy into this spin.
Assuming your math is correct, which is debatable, Kinect 2 is far more capable hardware on a much more powerful box. The 360 didn't have much to spare for the Kinect workload and the old Kinect technology is less precise and accurate than the new time of flight technology.