It could work, but it couldn't be a "new console" in the sense that it replaces the Wii U. It would have to "expand" the Wii U rather and expectations would have to be managed.
What it would be is this:
Wii U - Regular system, same as today, $199.99 or less by fall 2015.
Wii U "Pro" - Basically a Wii U chip + a high end AMD GPU in the box + 8GB RAM. $349.99.
The GPU would be higher end than the PS4 or XB1, lets say 2.8 TFLOP processing power.
The Wii U Pro plays the same Nintendo games as the Wii U, except when played on the Wii U Pro, they get a resolution boost to 1080p, 60 fps, anti-aliasing etc. Maybe even a bump to 2K or 4K resolution depending on the visual complexity of the game.
It has a higher end OS maybe developed in conjunction with Google that has more set top box functionality.
The main difference would be that third parties would be able to port their higher end PC engines, ones that may even have trouble running on the XB1 or PS4.
And the expectations would have to be realistic here, you're not going to sell 50 million Wii U Pros. Maybe by the end of the generation you have sold 22 million Wii U Pros + 25 million regular Wii Us ... that gives you 47 million systems to play Mario 3D World on (SNES size userbase).
In that sense it *could* work, but you can't alienate existing Wii U owners by killing their console. They have to be getting the same Wii U Nintendo games they were going to get otherwise.
