Truth is it will come when it is ready.
We always want the latest zelda as soon as possible but remember that Zelda has always been a waiting game. Anticipation is part of its DNA.
The thing is, I don't think, this time around, Miyamoto is interested in building a Zelda. I think he wants, once again, for it to be created. To get to that place they need a lot of time.
Miyamoto said they're not yet at a stage where they're building the graphics, or the story very much. They're focusing on gameplay. That says to me they're still on a quest to define what the next Zelda will be about.
Normally you have a concept of a game way in advance of developing it. That was the case with Twilight Princess, where they wanted to make an Ocarina-ish title. It was the case with Wind Waker, which was inspired by chinese art. Right now they want to rediscover Zelda, and this has been, more or less a demand from the public.
This kind of thing is not a given, which is why Miyamoto is focusing on experimentation right now.
Trust me, this game is a ways away. Just be grateful that we'll get a DS Zelda in the mean time.