So in June 2015 Miyamoto stated in an interview that they had footage ready for Zelda U that could be shown at E3 but Nintendo decided to not show it because they wanted to make shure that what was shown could meet the actual possibilities of the Wii U, now that we know that Zelda U is coming also to NX I think it's pretty obvious what was going on at the time: Nintendo focused development solely on the NX version, so they couldn't show the Wii U version because it was "early" in development and they weren't shure what kind of graphics they could get on a less powerful hardware, this is also supported by the fact that the Wii U version isn't coming out this holliday season: that's because it isn't ready, while the NX version most likely is almost done!

It's the other way around.

This.Pretty sure by the time E3 2015 came up, they knew Wii U was a lost cause, so they moved their resources to NX, and as a consequence making a NX port of Zelda U.So they couldnt show the game that early

I'm sure the WiiU version is done by now. What they are doing now is porting it to the NX. Hell, with all the time they have taken, I wouldn't be surprised if both versions were already done and they were now working on another project.

Because they just love teasing us. They love lying at us.
Oh, and you don't know what is their new plan: they will show Zelda at the E3 as their big focus so Nintendo fans create an impulse to buy it no matter what as it is the next must buy, and when the NX version is showed, they are going to make many of us to buy the new hardware with the game to get the best version.

They know how to manage us.

Or zelda wiiu is using a NX's spécification, or it's multiplayers game mod like triforce héros, and perhaps it's playing cross plateform wiiu / NX...

That's nonsense. It is a Wii U game ported to the NX and not vice versa.

Sounds like you thought wrong then.

If the Wii U version was in any way behind the NX version in development it would've simply been canned.

No way, it was definitely intended for Wii U from the get go. I believe in either 2012 or 2013 was when it was first announced to be in development as the obligatory Zelda every console gets. It wasn't until Smash and Kart failed to sell Wii Us that they decided it was a lost cause and better off on NX which'll be advertised as it's primary platform. I mean why else would they go from footage at 2014 E3 and Game Awards to literally nothing for almost two years.

I feel that it's more like the Wii U version was delayed so the NX version can get hyped up as well

They definitely wanted to release the game for Wii U in 2015 but delayed it and found that it would be a good idea to double dip