I think most people are underestimating Sony. In Lifetime sales,the PS3 will definitely overtake the 360. We keep seeing better exclusives for the PS3, bluray will become more popular, and the PS3 still has 2 price drops left, while the Xbox is already at $200, and I don't see them going to $150 again unless they are really desperate. There is a reason more developers are starting to utilize the PS3 as the lead titles, and this will only continue.
On the other hand, I think Kinect will sell a good amount, but not as well as everyone thinks. Kinect is directed to the casual crowd, and if the rumor of $150 price tag is true, this won't be carrying that many Xbox 360 units as the $150 models will run out. That's atleast $350 for Kinect Xbox, and I doubt the casuals will buy Kinect, since nothing at E3 was shown that was really revolutionary to people who already own a Wii. Kinect totally discards hardcore gamers.