Yeah, I don't really understand why Link is the only one who can defeat evil. If another villain takes the place of a prior oppressor and Link's incarnation isn't anywhere to be found, does that mean that nobody else will ever be able to take down the evildoer? That Hyrule's denizens would have to live in fear and doubt for years as they await the next Link?
It'd be amazing if Nintendo broke traditions with Link just once [to see how it goes] and replace him with an unexpected hero of sorts. All the while the land would be in turmoil, the fear evident towards almost anyone, and this character would accomplish tasks to help them overcome their apprehensions--as a system of voluntary sidequests of course. In this way he or she would be like Link, but not him exactly. And they would mainly set off to explore Dungeons, gather items, and ultimately face off against the antagonist, as before.