I'm one of those people who believe that there will be a dual release of Zelda U on Wii U and codename NX next year. Now zelda may not be able to attain the sales of mario and pokemon but in terms of its developement cycle, cost, production values, ambition and scope it is their most prestigious franchise. So Zelda U is a very important game for nintendo, too important to put it solely on a dying system. So an NX port seems logical and next to certain. Also i don't understand why some people dislike this idea, it is not like Nintendo is releasing the game on PS4/Xbone is it? It is being ported to a system that will probably be supported and valued by nintendo and nintendo fans far more than the Wii u has ever been.
Now which console to buy it for, I can say with certainty that i will buy the game for both systems. The Wii U version because that is the system the game was originally created for and because of the gamepad integration and the NX version because of the different control scheme and the higher technical performance. I know other people will differ and probably think it is a waste of money to buy the game twice but thats just me, so anyway what system will you Zelda U buy it for.
On a side note i do hope nintendo releases the full experience at launch instead of wasting time with dlc. As soon as production of Zelda U is finished i hope they have a rest then immediately crack on with the next 3D home console zelda and make sure it releases no later than 2020.