Ahhh yes, true.

Price point will be key too, $250 for that 3DS was a disgusting launch price. 

So a port of a game that wouldn't make you want to buy one piece of hardware is going to make you want to buy another? Don't get the reasoning.

lol nope. The 3ds is owned by many kids/none nintendo fans-

Almost every nintendo fan owns a wii u. The software is great btw (splatoon, Mario kart 8, 2 Zelda Remasters, Hyrule Warrios, Smash 4, Mario 3d Wörld, Bayonetta 2, Lego City Undercover, Pikmen 3, New star Fox coming, Pokken Tournament, Mario Maker, Xenoblade X, The wonderfull 101, Fast Racing Neo).

There isnt much left beside Metroid and F-Zero. I doubt Nintendo can suprass this lineup with the nx.

It doesn't hurt that's for sure.

The bigger thing it buys Nintendo is TIME. If they have Zelda in the launch window, then you don't need to break your back rushing a Mario platformer for launch, and if you can launch Mario Galaxy 3 or whatever in the post launch period that means the game that you were rushing before to make the post launch period can now slide into summer and so on and so on.

It's a domino effect that basically gifts Nintendo an easy launch and allows them to beef up their post-launch, post-launch summer, second holiday season, etc.

Actual new 3D Mario will be right on time to be launch title for NX too, because development of 3D Mario games last around 2.5-3 years, and Mario 3D World was launched at end of 2013. IMO 3D Mario and Zelda U port together would make very strong launch window, and after Wii U they really need to have very strong launch titles. Tomorow we will know if Pikmin 4 is Wii U or NX game (if they don't announce Pikmin 4 tomorrow most likely is a NX game), so Pikmin 4 easily could be in launch window too. Also we had that rumour saying Namco is preaparing Smash Bros 4 port for NX launch. 

I am pretty sure Nintendo will prepare some post solid launch titles too, they will definatly not want to repeat Wii U situation.

Of course. Just look at Twilight Princess.

If NX will release this year, Zelda U will have a huge Impact.
If NX will release next year, it would also have an Impact, but not as huge.

If NX is a home console, will Zelda U help it? Certainly. Will a port of Zelda U help it? Not much, if at all, since backwards compatibility already cover that.

Highlight in Bold. 

If that other piece of hardware is going to (or at least looks like its going to) have a better life then yes, its a simple premise of investment. I'm not buying NX solely for Zelda or any one game but it having Zelda at launch will make my purchase more likely especially as an impulse purchase. New hardware with a potentially bright future is of course more exciting & enticing then hardware nearly dead with only a handful of notable releases per year.

Of course that would help, it doesn't matter what it is, it's still an extra game. How could a console without Zelda do better than a console with Zelda? Similarly, WiiU did better with Nintendoland than it would have without Nintendoland; even if one person bought it because of it, it helped!