The only thing that happened is the new Mario game and more people aware of it being a different console and not a new controller for the Wii. I think it could sell 3 times this year what it sold last year, because of a higher baseline and Mario Kart and Smash Bros selling millions by itself.
The problem is the following years, all they would have remaining is Zelda, + the lesser franchises (if they decide to make those games) like Star Fox, Punch Out or F Zero.
Basically, the Wii U will run out of ammo this year.
To continue selling well after this year they would need something like a strong price cut.
edit: I thought it had sold only 2.800 million units like year, not over 3 million, in that case I don't think it can sell 3 times what it sold last year.
