Nintendo is basically forced to release it for both the Wii U and NX, awkwardly transition it to the NX with old tech and system specs; and without Gamepad capabilities (unless the NX has a Gamepad of it's own). This was slightly easier for Twilight Princess because the Gamecube and Wii had similar specs.
http://www.zeldainformer.com/news/forbes-wii-u-only-zelda-game-would-be-a-mistake
Already posted?