This time last year we didn't know about Mario 3d World or the new Zelda. I expect there will be more surprises next year. In terms of sales I can't say. I bet it will steadily get better and better as the games to cost ratio makes sense to different thresholds of gamers. Maybe have sales comparable to the Gamecube.
People who are complaining about the specs are dumb. The first party games on Wii U look fantastic.