It may be that the problem is not with the Wii U but with consoles in general. The availability of smartphone and tablet games may have changed the gaming landscape permanently. Game enthusiasts may turn up their noses and point out that mobile device games lack the diversity of controls and graphics quality, and most of them are simplistic compared to mobile games--which is true--but it is unclear just how much that means in terms of the market for consoles in the $ 200+ price range running games in the $50+ price range.
For many casual gamers, mobile games are good enough, considering that they run on a device that you already own, so you don't have to buy dedicated hardware, and the games are about the price of a candy bar. Each game may not have the depth of a console game, but if you get tired of one, there are plenty more. And at the other end, the true gaming fanatics play on computers, not consoles.
It may be that consoles will end up being neither here nor there, appealing to a diminishing market of moderately enthusiastic gamers that is too small to yield the profits required to justify the sort of massive development effort needed to create games with the graphics and play sophistication that console gamers expect.
Of course, Nintendo's systems have never been hard core--they've always been more oriented toward families, so perhaps Nintendo is more vulnerable to competition from mobile device gaming. On the other hand, so far there doesn't seem to be a huge degree of anticipation of new gaming systems from Sony and Microsoft, and both companies seem to be having difficulty articulating just what their new-generation systems will offer to convince consumers to shell out hundreds of dollars in up-front costs for new consoles.