Illusion on 14 December 2014
Also, don't forget that two years into the Gamecube's life it had two price cuts and was already being sold at $99. The Wii U really hasn't seen a formal price-cut yet (as long as you exclude Nintendo dropping the 32GB model down to $300). I think next year we will for sure at least see a Wii U price cut, maybe with even a $200 "slim" version getting introduced. This could have quite an impact on sales.
Also don't forget that games like Mario Maker, Splatoon and Star Fox will be getting released next year. On the surface these games don't look like big console movers but I think the potential for at least one of these titles to catch fire is pretty high. I mean, what if Splatoon turns out to be the "next" Portal?
