I think casual gamers will go with Kinect next gen. I don't see Wii U having the casual appeal. There's definitely a perception among the Wii Fit Mothers (at least those I know) that Kinect is better because you don't have to hold anything, and holding that Wiimote is now annoying and they don't even get the Wii out anymore. But Kinect looks neat.
Casual gaming on a device connected to the TV will always be around, and the more motion controlled it is the greater the point of difference from other devices. Kinect wins here because no controller = preferred for most casual games.
My own favourite casual games are Buzz and Singstar. For those a hand held input device is essential, though I suppose the Kinect mic could be good enough for a singing game, still lots of people like holding a mic when they sing.
I think the casual crowd has diminished for consoles, but there's still quite a few out there.
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” - Bertrand Russell
"When the power of love overcomes the love of power, the world will know peace."
Jimi Hendrix
