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.