At this point nothing will turn the tides for the Wii U. Consumers aren't interested and there are no ambitious games: New Super Mario Bros, 3D World, Zelda, Donkey Kong - these are all "save" sequels. Nothing exciting to be seen. With the Wii Nintendo was bold: Wii Sports was huge, Wii Fit was huge, motion controls were new and inviting. The Wii U should be called "anti-Wii", really.
I hope people will stop demanding "hardcore" games from Nintendo at this point. Every single hardcore game failed, the only decent seller is New Super Mario Bros. U (and Wii Party U in Japan) and that certainly is no "hardcore" game. Nintendo designed the Wii U to attract the core gamers and the console failed miserably.