I would be quite surprised if Zelda wasn't in it. I'm pretty sure they did say that this game is in Hyrule, and as far as I can remember, all of the games that take place in Hyrule have Zelda. Heck, even the ones that don't take place there give Zelda a cameo at the very least. Also, LA and MM, where Zelda wasn't really present, were sequels to other games (ALttP and OoT, respectively), and this game is in a totally new era. To me it seems very likely that she'll be a main character.
As for her making the story predictable, well, in some respects that's true. If Zelda's in it as a main character, Link always has to end up saving her in some way or form, which sort of ties things down a little bit. In games like LA and MM, where he was trying to save the entire land, the story seemed a bit more open, like almost anything could happen.
Even so, they have found quite imaginative ways to incorporate plot twists around Zelda throughout the series. I wouldn't mind if she was in this one.
Hmm... Maybe she's the very thing that gets the ball rolling? I can see it now... Link is chilling out in the sky and happens to look down and see a hot Princess. After watching her for a while, he sees her get kidnapped by the bad guys and he's like "OMG! No you din'nt!" and jumps off the cliff to save her.
Ok, sorry, starting to get a little loopy here, but it might be plausible. If it's really the first Zelda game in the timeline like some people are saying, one would think it would have something to do with our favorite princess. I know Link likes a good adventure, but I think he'd need a pretty good reason to go skydiving.
Didn't they say something about Link not even knowing about Hyrule in the first place? If that's the case, he probably can't see Hyrule from Sky Loft, at least not most of the time. Also, I kind of imagine that either the Goddesses or Zordiana will be the reason for his departing to Hyrule. Of course, it very well could be Zelda's doing somehow: we'll just have to wait and see.