I think this would make the most sense going by Nintendo's logic.
Give the Wii U an "exclusive" Zelda in 2016, not upsetting the fanbase. Offer a superior version of the game a year later on NX, giving it a strong launch title for those who didn't buy a Wii U whilst also being a bonus to fans of the game.
If I was Nintendo though I would just focus entirely on optimising the game for NX, scrap the Wii U version. Thats obviously not in their nature though