Wii U probably won't sell more than the GCN, but around the same amount. Aside from sales similarities, I have the feeling that people will look back at the Wii U the same way they do that strange purple lunchbox... 'Hey its kinda weird with a funky controller and different design, but I'll be damned if the games are some of the best I've ever played.'
“What I say is, a town isn't a town without a bookstore. It may call itself a town, but unless it's got a bookstore it knows it's not fooling a soul.” - Neil Gaiman