The whole idea of the Wii U should've been scrapped. They should've called the system "Wii 2" for the sake of simplicity. They should've replaced the tablet with a wiimote and nun-chuck since launch. They should've had games that were actually made around using the controller and they should've gone all in with software development knowing that third parties were going to ignore the platform wholly. They should've targetted their main audience with the original Wii and not half-ass an approach to appeal to the audience of PlayStation or Xbox -- because that's not what Nintendo's audience is or has been for generations. They should've advertised more than just the controller early on (especially if they had went with motion controls again). And they should've made it cost $250 from the very beginning.
At this point -- it's too late to do anything for the Wii U. The best thing Nintendo can do is lose less money on it as they move on to its successor. They do that by taking out the tablet and cut their losses on it. Nintendo fans don't buy Nintendo consoles for the gimmicky controllers-- they buy it for the games. There's no sense in losing money on each console sold because of a controller that nobody is asking for.
Then they pretend that the Wii U was just a spinoff experiment until they made the true successor to the Wii.
The Risk is too high.
Releasing a new Console would damage the Nintendo Brand as a manfacuturer significantly. It it would essentially throw away a majority of its dedicated hardcore base for a much larger but unreliable mainstream market.
Coupled with the fact that the Wii 2 would get ZERO 3rd party support, it would fail even worse, and Nintendo would basically stagnate into irrelevance, rather than go Supernova like Sony could.
The idea is:
The system is being sold at a lost. The tablet is the main cause of this problem. The tablet is not selling the system. The system isn't selling well.
All those statements are true. If we remove the tablet:
The system is no longer being sold at a lost. The system is not selling well.
There's nothing left you can do for Wii U at this point aside from softening the damages a little. I never said to stop supporting it and move on to the next system ASAP. Rather they should ride out the system for a 5 or 6 year lifecycle and push hard at the causal market that WORKED for them with the Wii. The system won't sell on par with the Wii (its success was unique and can't be duplicated), but it would sell a hell of a lot better than the Wii U. At the worst it would sell as well as the gamecube.
edit: Feel free to replace the word "tablet" with "gamepad".