People seem to forget the PS3 was struggling at one time too.
Good games, good marketing, a good outlook on the business have turned that around. No reason Nintendo couldn't do the same thing.
But, this time Wii U don't has that horse power to generate Visuals in compare to PS4/Xbone/PC. Wii U will sell only for their IP's and its not enough to sell more units. Also PS3 had advantages like Blueray, Horse power compared/higher than xbox360, they had New exclusives, and good 3rd party support, whereas Wii U just gonna has only one advantage of their IP's and its not enough to get sales similar to PS4/xbone. Wii U will sell but not like PS4/Xbone.
Multiplats and horsepower aren't what's going to sell the WiiU. First party games and the occasional 3rd party exclusives/collaborations (such as Sonic: LW, M & S: ATOG, B2, SMT x FE, lego City Undercover) plus advertising is what the Wii U needs.
And what do you mean "this time" Wii U can't generate visuals compared to Ps4/Xbone? Wii could when compared to PS360?
When it comes to the power gap Wii U is in a WAY better position compared to it's competition than Wii ever was.
I think the audience for third party multiplats is pretty much all but gone from Nintendo after years of being non-factor in that area. People who want the big multi-plat third party games are virtually Sony/MS only these days.
See: the PS4 version of CoD: Ghosts outselling the Wii U version in the UK charts even though the PS4 isn't even out yet, lol. Wii U is basically a non-factor.
Nintendo's challenge this gen is really going to boil down to how many of the casuals they grabbed with the original Wii they can convince to come back and pay $200+ for a Wii U in the post iPhone world.