I think this could do OK ...
PowerVR GT7900 type GPU (or AMD equivalent), runs at full 800 GFLOPS when played at home (plugged in), automatically downclocks to 400-500 GFLOPS when played on the road.
4GB LPDDR4 RAM + 32-48MB eDRAM
New controller. Yes it's a portable, but it also has a new controller for home play. Possibly the controller can also be used on the fly.
Can wirelessly send a video signal to the television (the reverse of the Wii U)
6-inch LCD display (single screen)
Custom Nintendo OS, but runs a Android back end so Android apps can be ported very quickly, they can only be autorized by Nintendo, however, who gets a nice royalty fee surcharge on each download.
$249.99 MSRP. Same launch price as the Wii, except you're getting a home console and a portable all in one.
But I get the feeling Nintendo will go even cheaper on the GPU/RAM unfortuantely.
I agree, or something similar with ARM CPU that is more capable and simpler than Wii U CPU.
I only don't agree about new controller, because you already have controls being portable and home console in one and Nintendo will want to have most affordable price. But we have controller that can be bought separate, maybe even Wii U Pro controller support.