Honestly, I think a lot of Nintendo's problem is simply not releasing enough of their games to the broader audience. It seems like have a very racist, anti-American, attitude at their core (like I used to pick up from a lot when I read translated Japanese periodicals...) and likes to hold back a lot of it's best stuff. There is this perception that Nintendo has a bad relationship with third party developers and chooses only to focus on a handful of key, recycled, franchises that do little to innovate (but to be honest, in a lot of cases they don't have to, their format works perfect as it is, which is why they haven't messed with it. Sort of like nobody has messed with Chess. Innovation for the sake of innovation is itself a problem... but a whole different discussion), in reality they have a lot of games they just never see a US release or become known here. Check out Gamefaqs list of Wii games some time and you'll see a number of decent ones that just never got released in the US. We pretty much had to fight tooth and nail to get "Xenoblade" released in the US, and really whining console manufacturers who can't move software have no valid complaints where we haven't seen official releases of many "Super Robot Taisen" games in the US (and those we have gotten for portables were not well promoted or taken care of), and those are some of the most frequently translated games passed around under the table by "pirates" into areas they won't be fairly released. Heck, I myself being a series fan wanted the Wii "Fatal Frame" game but that one got cancelled. It seems like in some kind of inverse Bizzaro logic Nintendo simply decides not to push it's publishers to release the games people are actually likely to play in it's most profitable sales territories or the places it wants to expand.
As things stand now I suspect the Wii U is probably failing hard, much like Wii game sales arguably did, not because of the reasons that seem to be in play, but because of Nintendo's arrogance. I'd imagine there will be more than a few fine games for the "Wii U" that could at least cement it a healthy niche audience in the US and other territories, but we'll never see them released in those territories and most people will never know they exist. Something basically akin to Nintendo being willing to commit seppeku before ensuring the system's best titles make their hands into the hands of stinking Gaijin (especially the ones from America).
At least that's my take on the situation, not that I expect a lot of people to agree. See, I actually got a Wii, but it's spend far more time disconnected in storage than in use because there just weren't any games I wanted to play on it. What games I heard about that I'd want to play got cancelled, or were never slated for US release, so it was a complete waste. My attitude about the Wii U is similar, I refuse to even consider supporting a system that's administrated with that attitude. Put out some games I want to play, and then I'll consider getting it.... and honestly looking at a Wii there is no doubt those games will exist, it's just that they won't be released so I could play them, or at least not until I'm well beyond caring.