The omission of Just Dance 4, by my estimation, is a result of Wii finally going belly up. The lion's share of sales for the IP were Wii-centric... so, with WiiU (finally) on the horizon, I think it makes sense to see sales slow for it. I was surprised to not see it chart at all, though.
I do agree with the casual demographic has largely been lost. Lots of competition for free time these days, between digital streaming, mobile, TV, e-mail & web surfing, etc. Consoles are going to have bigger challenge in the next generation staying competitive with more demo groups than the core. And the hope is that the core demo doesn't decide to jump to PC.
The next generation will be interesting to observe. I'm not sold on a doom-ish outlook, but am relatively confident in consumer contraction and the need to lower the bar of expectations as we're simply not going to see numbers close to what we saw during this generation. The industry must adapt, and I do believe that it will.