Nintendo dropped the Wii because the casual fad fell into a slump and the allure of the Kinect took the casuals away. Gimmicks tend to do that. 3-4 years of strong sales with a limited supply then, bam.....the fad wares out once everyone has run the train on it and moved onto the next thing. This is also why MS has to bundle the Kinect. Watch and see what happens if they don't bundle it next gen. The Wii U could've come later, but they decided to beat the other consoles to the punch because third parties were demanding newer hardware and Nintendo was going to give it to them, just on their own terms....underpowered.