Link the 13th, I don't mean to sound rude at all, but it's impossible for something to both stay the same and evolve.
And I think this is cool, with
PH and
TP being "the last Zelda game of their kind" it's fun to imagine what sorts of changes we will be looking at.
To me, a customization system sounds like a simple next step. It's not quite as jarring as a change of time period, but less arbitrary than just changing the main character. I hate turn-based RPG's, but I love the selection that RPG's have.
Perhaps the Master Sword has a unique material and attribute, and is not customizable, that way we could still customize but also need the Master Sword.