"I can't help but think that it would be better if Zelda Wii U did release on NX. I just think that Nintendo could make the game better if they made it for NX (assuming NX has significantly higher graphical capacity than Wii U)."
Nintendo has had a hard enough time developing games on 7th gen level hardware. A more powerful piece of tech won't really make a big difference in terms of Nintendo's own development. Nintendo still hasn't pushed the Wii U to its limits. Not one Wii U game looks better than the best looking PS3/360 games.
This is an excellent post and it perfectly describes the problems with Nintendo rushing to release the NX.
On the Gamecube, Metroid Prime I and II, Star Wars Rogue Squadron II and III, Resident Evil all pushed the GCN well past what people were expecting graphically. I think at the end of the Gamecube's life people really felt that the hardware was starting to hold back the games. Aside from Xenoblade, I can't think of much that's pushing the Wii U graphically (Zelda and Metroid could have gone a long way to help here). Even more importantly, the gamepad has not been fully utilized and now that we're finally seeing games like Mario Maker and Star Fox that might start to take advantage of the gamepad we're seeing signs that Nintendo is already done with the Wii U.
Even the Wii saw a lot of maturity with its motion controls. I really felt tapped out at the end of the Wii's life and that Nintendo did all that it could with that console. PS3 and X360 had amazing things done with those consoles that really made people excited for what's next. N64 had an expansion pack to push it's graphics past what it was meant to do. SNES had a chips placed inside of cartridges to expand the capabilities of the console. All of these consoles cried out for something new at the end of their lives. I don't see any of this from the Wii U. Like you said, I don't think that Nintendo has even figured out how to make HD games in a reasonable timeframe yet much less make a proper open world game. A newer console is only going to make the development process even harder for them since they haven't even figured it out on 7th gen hardware yet.
Now, Nintendo may have some really interesting ideas for what the NX will be, but I also want to hear why the Wii U was holding back the types of games that Nintendo wanted to make. At this point, it doesn't look to me like Nintendo is anywhere near pushing the limits of the Wii U. If the NX is primarily being released for financial reasons then the Wii U is going to be looked at like the Sega Saturn. Moving Zelda to the NX in any way will only make it look more like Nintendo is ducking and running from the Wii U. Yes some fans will come back, but when you take people's trust for granted you can find yourself out of a job pretty quick.
I hope that Nintendo does the right thing and continues to support the Wii U by announcing some high quality 1st party titles that we do not yet know about.