Are you saying that Nintendo are liars?

To me it wouldn't make a difference as i didn't buy the console for a specific game.
Nonetheless, i understand those who did and may feel that their investment could have been different.

But the fact is, even if it comes out on NX, Wii U owners are still getting the game. And if TP could be used as an exemple, you really won't feel cheated if you stick with Wii U to play the game.

NX is not even confirmed to be a console, its probably just a special nintendo service device, and i dont think Zelda Wii U will be released on the next console. Do you see Skyward Sword being released on Wii U because it was released one year before Wii U's release. and they could just included the Wii Motion plus controller in a bundle.The reason why they did it because of twilight princess is of the bad sales of the gamecube and they wanted to try out new things with the wii remote and we are still in the middle of Wii U's Life cycle, not the same thing as the gamecube. I think Nintendos next home console will be available 2018.

It probably won't. But in a hypothetical situation where it does, even if it's just a double release like Twilight Princess, the Wii U will probably go down as one of Nintendo's most hated consoles :S

Why are people so sure it won't be released on the next console? There's at least some evidence pointing in that direction:
1) Zelda has always been a holiday title. "Not in 2015" means it will be released in November 2016 or later.
2) The Wii U is selling bad. There's a point at which it won't make financial sense to keep it as their current gen console so it wouldn't surprise me if we saw a new home console in late 2016, together with their next handheld - especially if both are connected in some way (otherwise the home console would be magnitudes more powerful if they released it a year after the handheld console)
3) They've already done a cross-gen release with Twilight Princess, why not again?
4) They won't even show the game at e3! Why wouldn't they show a game we've already seen before? Yeah, there's marketing speech ("only 2015 games at e3") but why believe that? Maybe they are changing platforms or the game had some serious restructuring going on behind the scenes.
5) Zelda games always get delayed.

I'm not saying this will certainly be a cross-platform release. But right now I'd say chances are 50 / 50. Just my opinion, though.

the reason tp was on both systems is that the wii was very similar to the gamecube in terms of hardware and perfomance. i doubt nx will be anything like the wii u (it will be much more powerfull or arm-based)

Yes, it is confirmed to be a console. 

“Though I cannot confirm when it will be launched or any other details of the system, since I have confirmed that it will be ‘a dedicated video game platform with a brand new concept’ [as stated during the initial announcement] it should mean that we do not intend it to become a simple ‘replacement’ for Nintendo 3DS or Wii U,” Iwata told investors in a now translated Japanese Q&A.

http://www.nintendo.co.jp/ir/en/library/events/150508qa/02.html

Oh, yes. I wouldn't trust Nintendo anymore with promises. And since I can't trust if the NX will fail or not. Wait a few years to even play the game.

So....how is the situation different with the Wii U then? Wii U sales are actually worse than GameCube...

My view of WiiU has already changed significantly. While I will reserve final judgement for when the generation is over and the system will have had all it's biggest games, it still doesn't look good.

While 3D World for example is great, it wasn't the grand ambitious 3D Mario game-changer like Galaxy was before it, or 64 was before that. I know it was never supposed to be, but it means the WiiU goes without a game of such caliber. WiiU also never had a revolutionary new game concept, easiest example is Wii and it's signature series of course, but WiiU never had this 'must have' new thing. For now, the system to me feels like it's something they made to pass the time until they come up with the 'real' new console, to tide us over while they continue their 'real' development. A stop-gap system, if you will. There's fun games sure, but nothing that's really a 'classic'. For now, I see only Mario Kart 8 as a real attempt to bring something that evolves from it's predecessors.

If Zelda then also wouldn't be exclusive to WiiU, or worse, wouldn't come at all, that would without a doubt cement the system at the bottom place of the Nintendo-system-ranking for me. If I could rather get the new game on something else (something more powerful and advanced even), that would certainly make me question why I ever got the WiiU in the first place, if I couldn't have lived without the games it got. I didn't think it would ever happen that I would consider a system worse than what I found to be the very disappointing Gamecube...

But.. We're not there yet. As it stands, Zelda U is still a 'U', and exclusively so. I don't think the game will release later than 2016 (probably November 2016) and I don't think the next system, whatever shape it may take, will release before 2017.