What Zelda really needs is a balance between size and and function. Xenoblade Chronicles was beautiful. I love the game. The overworld was boring. At the very least, I'd have appreciated a horse/motorcycle/tricycle/SOMETHING to make travel faster. Running across beautiful plains of nothing was good on the eyes, but still tedious.
If Nintendo could pull off a Skyrim-sized world absolutely littered with secrets (hidden caves, optional dungeons, sidequests, mini-games, buried treasure, Easter eggs, etc.), it would be one of the best things Zelda has ever experienced. Apparently, one of Skyrim's joys was the wealth of things to do within the confines of its controls and nature. Unusually, quantity was its quality rather than just being a lot of simple stuff. I haven't played Skyrim yet, but that's basically what I've heard of it. The Legend of Zelda, meanwhile, takes numerous other factors into consideration, like story, cutscenes, evolved combat, puzzles within dungeons, puzzles outside of dungeons, hidden caves, and mini-games. I've heard Skyrim's overworld is a lot of emptiness. I'm alright with Zelda having a big overworld that's not as big as Skyrim's if it'll allow Nintendo more time and space to make the world filled with content.
But then they need to do it. The sky from Skyward Sword was supposed to be a big playground with lots of content (or at least it was interpreted to be as such), but it wound up being almost entirely useless. Goddess Cube Chests could easily have been on Skyloft's main island, and Link could easily have accessed the world below without needing to fly. The sky added little to the game. So if Nintendo promises an overworld filled with meaningful content...they need to do it. I'm not even confident they would, but it would be one of the greatest things to happen to Zelda. Imagine a huge Zelda overworld with dozens of hidden caves, a few optional dungeons, overworld bosses, buried treasure, and incredible views. It's got to happen, but I don't know that Nintendo is on board with it. Zelda's focus no longer seems to be exploration, but puzzles and combat - which were originally supplementary to exploration, not independent from it.
The Lost Woods could make particularly good use of an open-world mechanic. Subtle environmental signs (kind of like the flags from the Haunted Wasteland in Ocarina of Time) could point you in the right direction; stepping off the correct path would result in genuinely getting lost unless you knew the woods like the back of your hand. But if getting lost meant constantly finding secrets and pleasant surprises, it wouldn't be such a bad thing.
Zelda really needs an open world. Even if dungeon order is linear, to be able to go where you want from the beginning, minus the rock walls closing everything off, would benefit the series tremendously.