Why limit one of your biggest franchises, to a niche / dying console, just so those fans alone can have the game.
Just put it on both, because anything else would be silly. Personal gain and greed are the only reason anyone would want Zelda to stay exclusive on Wii U.
The NX is Nintendo's chance for hardware and software redemption among gamers and developers, and having a hugely impressive launch line-up with Pokemon Sun / Moon, Zelda, Mario, Splatoon, etc... all on the device means that it should take off like a rockets at launch.
There's a fairly decent size group of gamers who want to play Nintendo's latest games, but they don't want to buy an overpriced Wii U, that had a potential successor announced at E3 2015.
And on top of that the majority of Nintendo gamers prefer a handheld, which is why 3DS is outselling Wii U nearly 5:1, and why every handheld has always outsold its console counterpart. That's due to more than half of the audience being child gamers, but a sale is a sale, and you want your best product on your best device.
So to make everyone happy, put it on both.







