I think it's gonna take a while before we see a brand new Zelda HD. It's Nintendo's first time developing in HD, and Zelda is a far bigger game than, say, Super Mario 3D World. It's a problem the industry has left in 2006, but oh well.
I'm not so sure about a 2015 release. I'd say 2016 the earliest. And I wouldn't be surprised if it's not as "open-worlded" as previous entries and is a bit more linear.