I highly doubt this is happening. While it would benefit the Switch in its launch year if it was only released on it, Nintendo knows the backlash from Wii U owners wouldn't be worth it, even if most of them are already buying a Switch anyway most likely. If this were to actually be true then that is just a downright dirty decision towards the Wii U owners that bought the Wii U for games like this Zelda.
They're previewed and demo'd the Wii U version plenty of times as well.
edit: To be clear, I would not be surprised in the slightest if this is something Nintendo were to do since they have made plenty of dumb decisions in the past, i'm just saying that I have high doubts about it though because surely Nintendo knows how much of a PR disaster this would be.
