Because it's delayed quite some time, Wii U sales are dead and it would be a great launch title for the NX. Why release one of your biggest games on a dead console when your new hardware is about to release? It just wouldn't make sense.

Wii sales were dead in 2011.

Skyward Sword:

"Nintendo president Satoru Iwata revealed plans to release the game by the end of 2010"

"At Nintendo's press conference coinciding with the trade show in June 2010, it was announced that the subtitle of the Wii Zelda was Skyward Sword, and that the game would be delayed until 2011"

"On August 17, 2011, Skyward Sword was announced to be released in Europe on November 18, 2011, and in North America on November 20, 2011"

Pretty much the same huh? Were is the wiiu release?

BTW: Zelda SS release 2011. Wii U reveale: 2011. Zelda Wii U release 2016. NX reveal: 2016.

Also Skyward sword only sold 3.5 Mio units on the large installed hw base of the wii. because on wii most people were casuals.

Zelda will only be bought be the "hardcore" fans. And those already got a wii u.

Zelda wii u will sell the same, no matter if NX or Wii U. Just see how games like Splatoon, Smash, Mario Kart do sell on Wii U. The Wii U is an awesome nintendo games seller.

Wii U is destined to be lower than 13 million if NX releases next year and there are no new games for Wii U besides casual Dance 2016. GameCube has 21 million sales LTD.

Not every Nintendo loyalist bought a Wii U. Over half of them did but we don't even know how many are truly upset that Zelda U isn't exclusive anymore. I mean, we bought the Wii U when 8 million Nintendo fans didn't. We will probably buy the next system once we see Smash, Mario Kart, Splatoon 2, or Mario Galaxy 3 anyway. 

Zelda wii u is still exclusive. There isnt any NX announcement yet. 

Nintendo ONLY confirmed that the game will be on wii u.

Also im sure more then 50% of Nintendo fans got a wii u. Yeah, gamecube had more sales, but the Nintendo console installed hw base decreased from generation to generation. Some math:

NES: 62 mio

SNES: 49 Mio (-20%)

N64: 33 Mio (-33%)

Gamecube: 21 Mio (-37%)

Wii u: lifetime probl. ~13 Mio (-40%)

No wii because the system was most likely bought by causals who want to play wii sports and co.

So you can see a big decrese in each generation of nintendo console which are aimed at "real gamers". 

That said, its very likely that the majortiy of the nintendo fans now a days already got the wii u and only ~3mio fans are missing.

Yeah, but what about Splatoon? It's still a system seller.

Easy. We knew Twilight Princess name and launch window before deleay, even before the Revolution. Now, we don't have anything more than a 45 seconds teaser and off screen empty footage. Not even a proper trailer, and the game is already delayed to TBD. Not 2016, not 2017. TBD.

The PR for the TP delay was more precise than the one for Zelda HD. It's easy to connect the dots if you take in count the rumor of the NX releasing next year and being also in some form a homeconsole.

And btw, please, do yourself a favor and not compare this situation with SS or anyone can debunk your theory with 2 simple arguments: Wii was still selling more than Wii U even at being called dead, and second, 25th anniversary.

sure its not a 100% never happen thing. I just said, in my opinion its unlikely.

And Nintendo could do more damage with a NX port as it would help. Most Zelda fans already got a wii u anyway. The sales from the game wouldnt be higher. Im very sure, that Zelda Wii U will sell more copies on wii u (exclusive release) as skyward sword sold on wii (100mio userbase).

Bring the game to NX and Wii u could also make people think: "Okay i already got a wii u so ill get the game for wii u and skip the nx, because Zelda NX will be again on NX and "NX-sucessor".

Also Zelda is not Nintendos biggest seller. Special as a Port. The wii doesnt did that well because of Twilight Princess. It sold that well because of wii sports. And Nintendo knows that. They tried to do the same on wii u with nintendoland but it failed.

Game series like Mario Kart, 3d/2s Mario games, Smash and co sell ALOT better then Zelda games. So why bother with a Port of a wii u game if you could bring mario kart 9 on NX release instead ? It just would make ALOT more sense.

Some sales:

Skyward Sword: 3,5 mio

Twilight Princess (wii): 7,1 mio (rank 17 most sold on wii)

Mario Galaxy: 11,2 Mio

Mario Kart Wii: 35 Mio

Smash Brawl: 12,5 Mio

Mario Party 8: 8,2 Mio

New Super mario Bros wii: 28 Mio

Zelda is not a big systems seller. especially for a console that is aimed at the casual market.

Nintendo already got their "hardcore system". its the wii u. Where all the Nintendo fans are at. Thats the perfect console to release the new zelda on.

Do you truly believe Twilight Princess sold that well on Wii because Wii Sports? What about Skyward Sword flop?

we will see. Im not 100% it wont happen. I just think its unlikely.

And its ridiclous how many people already think the nx release is 100%. its not. Its at most 20-30%.

It's not 20-30 or 100%

We are connecting the dots. We are not going to act surprised when we are living the same that happened 10 years ago. We learned our lesson.