At this point during the same time frame, the Dreamcast sold twice as much as the Wii U. Even the most die hard nintendo fanboys admit that the Wii U is an utter failure. I honestly think it does more harm than good to keep the Wii U going. People who actually bought one WILL buy a new nintendo console no matter what, so how long until Nintendo realizes that by keeping the Wii U around they fall deeper into obscurity.
Announce a successor already, have whatever remaining wii u games come out for the new console, and cut your losses.