Firstly, they have the 3DS to fall back on in worst case. They will still be profitable this gen overall.
Plus, I don't think the Wii U is doing as bad as people want to make it out to be. It is literally the console with no big games. It has 3 that I'd consider non-niche. 2 Mario's & a Zelda remake.
Once more games release and prices are dropped, Wii U should at least pass GC numbers. The system should make some profit by the end based off Nintendo games.
I also expect an add-on similar to the Balance Board from the Wii. Vitality Sensor? Haptic tech in the GP? A free dog with every purchase? Nobody knows but I'd bet they have something that will be revealed soon.