OK made two big posts in the Gamesradar forums on this topic already, so I'm going to do a little copy and paste.
Yes, the formula is stale, but also, we have to remember that Twilight Princess is EXACTLY what we had been asking for for 10 years. We wanted adult Link, 3D, more realistic and not cartoony cell shading, and a longer adventure, more like Ocarina of Time, only as an adult Link with a few new items tossed in. And we got want we asked for.
We even had a console, and thus, control scheme option.
Now, I love Zelda, but I also agree that it needs to shake up things to make sure that it doesn't go stale. Please don't ask for a more serious, brooding Link, or else it will most likely turn out like the disappointing Prince of Persia: Warrior Within. Why did that game suck? It improved the one weak point of Sands of Time, the combat, yet it still sucked because it destroyed the storybook elements that made the first 3D Prince of Persia so great and such a magical experience.
If you want brooding pretty boys, go watch Twilight or play the terrible Castlevania Judgment. Seriously, Judgment has the Hot Topic make over that Castlevania never needed nor asked for. Its one of the worst games I've ever had the misfortune of playing.
Brooding heroes is one of the worst cliches in the video game industry right now, it's not the cliche that Zelda needs in order to escape being a cliche.
and here's what I wrote in the gamesradar nintendo forums:
I think it would be interesting if the plot actually got a little more complex, and Ganon was more of a tragic figure than ultimate evil. Maybe Ganon would be a fallen hero, someone who took the Triforce of Power with good intentions, and Link would have to wonder if it's his fate to end up like Ganon...
I think that, yes, the next Zelda most certainly has to mix things up. I think the Fable 2 direction would have promise, I dont know though because I haven't played it yet, probably early next year, and I think that having Zelda as a playable character, and not some helpless princess would be great. Maybe something like Secret of Mana, and have Zelda cast spells while Link is the main tank and both be playable. I think that style would also fit into the whole triforce of Wisdom and triforce of Courage roles that Zelda and Link are tied to. Plus, this way, if they adventure together, they can actually develop a relationship that makes you actually care about the characters. Plus, two characters to solve puzzles, it's been done with Four Swords, but this would seem more natural to me than Four Swords.
Also, I think it's about time that they dropped the midi/synth music and sound effects, Zelda has some of the best music ever, and it should be orchestrated. (Just listen to the complete orchestral Zelda music in Brawl and compare it to Twilight Princess) Also, voice over. Link can probably get by as a silent protagonist for another console generation, but the rest of the world would benefit from voice overs. Think of all the accents! I think Gorons should have a thick Scottish accent, while Zoras would be more prim and proper, and even a little prissy, like Abe Sapien from Hellboy.
I actually like to think of Shadow of the Colossus as an unofficial Zelda game. I know its a sequel/prequel to another great game for its time, Ico, but I think of Shadow of the Colossus as an unofficial Zelda title.
I mean, you don't collect items to solve puzzles, but I had a stronger connection with Agro than I did with Epona, and frankly, each of the Colossi and the environment that you find them in is a puzzle that you have to solve. And to me, puzzles are the core Zelda experience.
The other way to shake up the Zelda license, IMHO, is to actually license it out. We already have Links Crossbow Training, which I think is fun, and worth playing, even though you can beat it in about an hour or two. Still, license the game out a little more, we had Smash Bros Brawl this year, but I think a few unofficial Zelda games will help us appreciate the core Zelda games more.
Personally, I'd like to play a god game, like a fantasy combination of SimCity and Black and White, where you play as Link, right after he takes up the complete triforce in A Link to the Past, and has to restore both the Dark World and the Light World to glory. Changes he makes in first the Dark World, because that was the most fucked up, will effect the Light World, sometimes negatively, and it becomes a balancing act to keep the two worlds prospering positively at the same time.
After all a hero's work is never done. And, because it would follow a Link to the Past, it should be on the DS, and the two screens plus stylus would work perfectly with my light world/dark world god game balancing act.