I think that the next Zelda needs to improve its the story. I never get tired of having the Master Sword in the games, Ganon, or the Triforce, but the story should impact the game more and actually be very powerful. Wind Waker was a step in the right direction in terms of story. It was simple, but very effective and entertaining. Link shouldn't speak, but I think the other characters should. I think the combat in OOT/WW is perfect, but I don't want any more recycled bosses. Wind Waker copied some of OOT's bosses, and they needed all new ones.
Adding Epona to OOT was such a great idea and it worked well. It seems Link once again rides a horse in this new game, so transportation is covered. Another thing I think the new game needs is another trading sequence when you get a GREAT reward. The Big Goron's Sword in OOT was so sweet, I want something like that again. I want the old favorites to return of course, like the Hookshot,

but I want something new and fresh like the Gust Jar was in Minish Cap. I think this feature was in Majora's Mask, but I want to be able to replay dungeons easily, without starting a new game. The Spirit Temple in OOT is SO AWESOME, and I wish I could just play it whenever. I want the Ocarina back, if there is to be music once again. The Ocarina was simple, not like that Baton nonsense. It's much easier to quickly use the Ocarina than the baton.
I know this next Zelda will probably be pretty serious, but I want some humor. In Minish Cap, where the game makes fun of getting a green rupee the first time, "Don't Spend it all in one place!" I laughed and laughed, because it was a great Zelda joke. Ocarina had some funny stuff, too, like Darunia: "HOT! What a hot beat!" When he danced to Saria's song. :lol Another thing I think is done well in Zelda is the stealth sequences. Sneaking around in a barrel in WW or knocking out Gerudo guards in OOT is still pretty fun, and I imagine they could up with something in the new game.