Unless PS3 gets some great games to support it, it'll sell okay to some casual users who are willing to give it a try.
NATAL will sell a lot if they come out with a new SKU. X360 owners will buy the new sku because it's the new model. Also, Natal has a huge draw to the casual audience. NATAL will sell huge if they can figure out really simple and neat ways of using it. Such as no controls for running menus etc. Lets say you can rent and stream movies without the use of a controller. There's also a lot of potential for mini games.
It would take some huge flaws in Natals execution for it to fail.







