People love to overreact, and they take a look at the % of decline and shout "WII IS THE DOOMED!" Most people can't seem to look past the short term, and don't look at the larger picture. Wii could probably not sell a single console from here on out and be just fine. Nintendo stumbled upon a goldmine with Wii and has already made tons of profit, not to mention they hold a nice comfortable lead of 35 plus million on its nearest competitor.
The problem is, as I've said a million times, third parties haven't taken the call to pick up the slack, and especially with Nintendo focused on the 3DS right now, the lineup is almost non existant so far this year. But even with virtually no new games, Wii is essentially battling the other two consoles to a standstill this year, (PS3 has a slight lead, mainly because of it simply being available in more markets) which I find incredible considering the circumstances. So basically, Wii is just fine. In fact, it is more than fine.
What I am concerned about is Nintendo sort of resting on their laurels, and getting lazy with the Wii games. They're already starting to show signs that they have forgotten the formula to what made Wii successful in the first place, making/publishing games that only appeal to a niche of hardcore gamers like Metroid Other M, Monster Hunter Tri, Sin and Punishment 2, Kirby's Epic Yarn, etc. Donkey Kong Country Returns is a step in the right direction, but one game will not be enough. They need more games that show they are still interested in appealing to the masses of gamers/non gamers/ex gamers, and they've really neglected to do that for the past year or so, hence the sales are stuck in neutral.
