Mario and Taiko failed. This is bad. Wii U needs a phenomenal new game on the Pokemon scale to save it. And that probably isn't happening.
Stop this. Mario is "on the Pokemon scale" if not higher. Just accept that the Wii U is a failure in so many aspects and the reason it's not selling it's because of these aspects, which were caused by disastrous decisions like A) Same hardware as PS360 (which have a combined install base of over 150m), B) Confusing concept/marketing/presentation, C) Wii aftermath/lesson learned, and D) Retarded name.
They had years of advantage thanks to the unexpected Wii success, and they decided to throw it by releasing an old hardware worth nothing more than the first party titles, which is exactly what the Wii was after the initial boom. No game can "save" this console because there's nothing to save. If people buy it they will do it to play the first party exclusives and put it on the shelf, and the amount of these people won't exceed the 5m. Nobody with a PS3 or a 360 can possibly desire a Wii U for anything else than their few first party games, and that's no reason to spend +200$, especially with the PS4 and Xbox One out there, and the casuals have already forgotten the gimmicks and have moved to smartphones and tablets. It's that simple.