I don't think more Wii U's is necessarily the answer. Wii had a crapton of sales but didn't sell most 3rd party games regardless. Nintendo fans just don't want any 3rd party game besides the dancing one. It seems like most of these folks will only buy a game with "nintendo's seal of quality" xD.
Some will say it's because they don't like "dudebro" games but even a Japanocentric title like Tales of Graces did much better on PS3 than Wii despite the PS3 version coming much later and having a much smaller base to sell to at the time.
Conclusion: Nintendo fans don't want 3rd party games so why bother. They complain of them being nonexistent but won't buy them if they did exist. That what it seems like anyway.
"Dr. Tenma, according to you, lives are equal. That's why I live today. But you must have realised it by now...the only thing people are equal in is death"---Johann Liebert (MONSTER)
"WAR is a racket. It always has been.
It is possibly the oldest, easily the most profitable, surely the most vicious. It is the only one international in scope. It is the only one in which the profits are reckoned in dollars and the losses in lives"---Maj. Gen. Smedley Butler