As a lifelong Zelda fan, I can say that I share the apprehension that many feel when it comes to something like this. Link is such an odd character, because he never has talked, and aside from tiny little character quirks, he isn't very interesting on his own. Zelda isn't really about Link at the end of the day. It's the experience the player gets out of it. Link just happens to be the avatar in which you inhabit in the world of Hyrule.
That being said, I'm not terribly against the idea either. The problem lies solely with Link. Picking a personality for an iconic character that doesn't have a set personality is a risky decision.
I'm not worried about Link talking. I've been one of the people hoping for voice acting in a Zelda game for a long time. I also hope they get somebody fairly young. The oldest Link has ever been is about 17, so seeing somebody in their late 20's doing it wouldn't be a good idea. Link always had kind of the adolescent Peter Pan thing going on.
I would be thrilled to see some unknowns play all the parts, kind of like how Star Wars, Harry Potter, and other big franchises made the actors stars, instead of the other way around.
Though it could prove fatal to their career. When you get somebody unknown to play a character that is already iconic, and they fail to live up to the people's expectations, you get:
