I think NX releases this year but that's quite the exaggeration.

^This. They are expanding their brand exponentially. Hardly the sign of a company going out of business.

With dual release game will certainly sell few millions more than on Wii U alone, and definitely will effect on NX launch. Basically two things from Nintendo will profit in big way, it clear business sense, and basically dont have one negative thing doing that, also we already saw something similar with TP.

I'm not talking about target platforms. It's a wii u game.

It's a game made from the ground to Wii U. It will always be a wii u game.

From a business perspective, it makes zero sense to keep the new Zelda Wii U exclusive. Just my thought on this one.

Probably release on both, game held back so both can be released at the same time in my opinion. Happiness all round for Wii U owners and whatever NX is.

This is fairly obvious if you remove emotion from the equation. The game will easily sell an extra 1.5-2 million copies that it wouldn't otherwise minimum as a NX launch title due to all the extra excitement that comes from being in a launch window and being the "go to" launch game. 

It also gifts Nintendo basically a "free" killer app for their NX launch window, which means the other game(s) they wanted to have in the launch window don't neccessarily have to be in launch. IE: No need to rush a Mario NX, because you have Zelda for launch, so now Mario NX can comfortably arrive in that post launch window. 

Like already wrote to you few times, just technically.  For intance most people consider TP like Wii game because huge majority of people played that game on Wii and game had much longer life on Wii, GC version was practically dead right after TP launched while Wii life just started.

Also, think about double dippers, I know many people who would get it both on Wii U and on NX if it released a couple days/months on Wii U first...