Similar to Final Fantasy 15 and Type 0 HD.

Good idea?

The Legend of Zelda collection for the Gamecube had a demo of The Wind Waker, so this is possible. It is definitely a good idea.
I will be getting Twilight Princess HD regardless.

That would honestly be pretty interesting! I wouldn't mind that at all.

(Though I have a feeling that a vocal group will condemn Nintendo for making such a choice, even though this has happened in the past)

That would make this game fly off the shelves more than before, surely.

Unlikely but that would be amazing

If Zelda is gonna be a complete open world i don't really see how, shouldn't they give us the whole map to play then? 

But anyways, Zelda U is a game that doesn't need a demo at all. People is already very hyped for it.

Could be a limited area of the open world, a area not even used in the final game, part of a dungeon and more.

Like somebody already said: Windwaker was also open world and got a demo.

The demo will boost twilight princess hd sales, not sell zelda u copies ;) Just like final fantasy 15 demo did.

That would be so unfortunate for me. Amazing for everyone else.

I don't think it will get one, I don't see how it would be possible... but anyway, if it happens, then I would consider buying TPHD, but only if the demo is big like FFXV's was.

Right now, I'm on the fence about Twilight Princess HD. If that happened, Twilight Princess HD would be a day one buy for me. I'm sure there are many others who would do the same, so that would be an amazing idea for Nintendo to do.