I think they could, but it would take a major effort, and depending on how soon the Wii 2 is releasing I'm not sure it would be worth the investment.
But if they were trying to rejuvinate Wii sales, this would be my strategy.
-Redesign at E3, accompanied by a large marketing campaign. I'm not sure what could be done, maybe add a HDD, make the console a little sleeker, etc. It would be more about making it seem like a major overhaul in the eyes of the consumer than actually changing the console a lot.
-Player's choice to fill in gaps during dry spells. The Wii goes too long (like right now in NA) without major releases. Releasing budget lineups will help fill those gaps and make the console seem like a better value. (My strategy, release Super Mario Galaxy, Brawl, Animal Crossing, Mario Party 8, Twilight Princess, as the first players choice titles as soon as possible).
-More big games (esp for Japan). In Japan Nintendo has the start of a strong line up for 2011 -The Last Story, Kirby, Zelda, Rhythm Heaven, Inazuma Strikers etc. They need a few more big releases such as Dragon Quest X to release this year and I think they'll be in good shape.
-Full blown Pokemon on Wii. They have one huge established franchise that has not seen a true release on the system. I think this would help the Wii out a lot worldwide, but especially in Japan.
- Vitality Sensor, or some other new and innovative accessory and game. I think they need to come with one more big Wii__ title that seems completely new and cataches on like Wii Sports/Fit.
- Price Cuts - I think there should be two this year. One to $179 in the start of April to prevent hardware sale from dropping to much, and another down to $150 in October to help drive huge holiday sales.
I think if they do all that Wii sales will rebound largely, not to the peak levels in 2008, but maybe between 2009-2010 levels, instead of experiencing another large drop this year if they don't try hard to prevent it.
I think all the things I suggested are possible (except maybe the Pokemon game), but like I said at the start, if the plans is for a Wii 2 in 2012 I'm not sure it would be worthwhile.