So the issue I've always had with this theory is that it would mean either the game releases in 2017, or NX launches in 2016. I always assumed (and still do) that NX would launch in 2017, so if Zelda U launches in 2016 it wouldn't really make much sense to port it. For Twilight Princess, it came out for the GameCube just a couple weeks after releasing for the Wii. If Zelda U comes out for NX a year after launching on the Wii U, I don't really see what the point would be, and hence believe it to be unlikely.