Zelda games have always had a mild allergy to change (most Nintendo franchises avoid breaking more than a few of their own conventions at every release) but as it stands now, the second a new instalment is announced it can be assumed that it will be set in Hyrule, fate has chosen a hero named Link and a spirit maiden named Zelda to combat their foil Ganon, Link will search for a series of relics that will break a seal and then search for a new set of relics after going through the seal, Zelda will be captured and in the final hour Link will confront Ganon in an underwhelming boss fight.
Link is always a silent protagonist, a quixotic evil wizard will do Ganon's bidding, there will be temples themed according to region, a staple of tools will return for the same utility over and over. With little exception the game is the same every time. So much so that the holes in the formula are starting to yawn unforgivably. The inevitable counterpoint to the repetition is that Zelda games are a canticle repeating the same story with slight differences each time. But since Ocarina of Time, the reuse of archetypes has been more of a grocery list than an homage to its roots.
Which makes sense in a way, the last time the series made any major changes was the move to 3D. Ocarina gave narrative purpose to its events beyond "Zelda's in trouble and Link happens to be the closest person to answer the call." At the time, Link didn't need to talk, Zelda didn't need to be a colourful personality, Hyrule was bursting with openness and life. Anymore though, even as Hyrule's borders have swelled and the mythology has been expanded, it's still copying from a template over a decade old. Twilight Princess perfected the form, and now that there's nowhere else to go Skyward Sword, in spite of the elegance of its design, can only be the beginning of the end unless the series reinvents itself again.
And it isn't as though there aren't plenty of directions for Zelda to go. Early on there's a desert where Link must activate crystals that will turn a small area of wasteland into a technologically powered industrial complex in a lush valley. Small glimmers of brilliance shine even when the procedure of unlocking and navigating each dungeon is still as hopelessly routine as the last six times. Even the effort to make Link into a person, the way that others interact with him is starkly different than the last title. Twilight Princess showed a Link that was a universally loved, reliable farm-boy whereas Skyward Sword gives us a bumbling, incompetent slacker with a crush on the headmaster's daughter. But the differences are only surface so long as Nintendo keeps giving us the same shell dressed in green.
The ideal Zelda game will have to shake convention as violently as Ocarina departed from Link to the Past. My ideal Zelda game would be one in a world run by Ganon, or in a alternate-reality revolutionary France, or in space. Player two would have the option of controlling a fully functional Zelda and Link would have his own dialogue. The temples and tools can stay but only if they are unrecognizable as their descendants. The point is that it would look nothing like the series is now and would have to stand on its own merits, not on its heritage.
Other series have been rightfully accused of re-releasing the same game biennially but at least with Call of Duty or Assassin's Creed one could argue that each new instalment adds more or intensifies the experience. But Zelda games change nothing, they take a set of pieces of previous titles, stitch them together in a new way and no matter how good the resulting Frankenstein monster seems it's doomed to eventually fall apart.