This was a pretty weak year for the Wii, the worst it has had. It is not, however, in the same company as the weakest one year lineups any console or handheld has had in the history of video gaming by any means. Just looking at this page gives one the idea of what 1/10 years would look like: http://en.wikipedia.org/wiki/Chronological_list_of_PC_Engine_games
That system actually has some pretty good games on it, but by the end things were really falling apart. If you took out Zelda SS Wii's 2011 would have still been a fairly good any year for the TG16, and it's not exactly the epitome of fail in gaming (just, you know, outside of Japan). Look at any year of the Atari Jaguar, for example. Don't make me bust out a list. There's all sorts of fail to talk about, this year for the Wii, as far as failures go, was either the least epic fail ever or the most for being ridiculously profitable while "failing."
Now, where the real failure does lie here is in the deteriorating relations with 3rd parties. By 2008 it was obvious Wii was going to come out on top AND that there was plenty of time for real 3rd party efforts to have caught on to the long developing trend, but even today I can hardly think of any. Most core games don't get ported to the Wii and the ones that do are often crippled in a way that can't be blamed on the hardware. Let's take, for example, the fact that online support from third parties has been pretty weak. Are they just getting complacent because Sony and MS will handle most of that? Well, a lot of them still produce plenty of PC games where they have to develop it themselves so, no, probably not. They're probably becoming indignant, because Nintendo won't pay for something that wasn't free a generation ago.
Basically, aside from a handful of examples, the only support they are getting now from 3rd parties is either stuff guaranteed to sell to people who don't care that they aren't getting a full-featured (graphics aside, even) version of the game available that is on other consoles, don't care that they are getting a a heavily altered spin-off of a game, or don't care that the game had such a low budget that it barely needs to sell at all to make some money. And if they fail at any of those three they think it's not their fault, it's Nintendo's.
What can Nintendo do to fix that? Throw a hell of a lot of cash out there to appease the third parties. And that's it. Dive back into the red ocean, admit they made a "mistake" and hope their timing is just right to take advantage of their relatively early transition. I've been a fan of Nintendo's through thick and thin, and it's time for them to win multiplat support back asap. This is the first year where I could just say "yeah, I didn't really care all that much about what Nintendo released last year so I played none of it" since, um, ever. I kinda want to play that new Kirby, but I don't actually care all that much, and Zelda and I parted ways after OoT was so much of what I didn't want the series to be. I also have about as much thought towards their 3P support (I'd like to try out Just Dance 3, or even one of the first two maybe), and that's just ridiculous because even if Nintendo walks away a tad early to support the next system 3rd parties tend to stick around longer.
Nintendo's real problem is with 3rd parties which, as a collective, have generally treated the Wii as a nuisance. There was so much potential and they quashed their own share of it because Nintendo wouldn't pay them to take the profits they could have earned. The industry is a damn shame from basically every angle, and Nintendo needs to lower themselves to entertaining that shame in order to survive the next generation because tablet controllers aren't nearly the revolution that wiimotes were by any stretch.