Haha some of those would be horrible, and I'll be honest, some of them I'd like to see

Adding optional voice acting
Setting Zelda in a modern day/futuristic setting, like FFVII

These would be daring, especially the second, but I think would reinvigorate the series

Introducing a female or non-Link character

And this, frankly, I'd never considered before, but now that I think about it... a female Link would be really cool. Certainly unexpected. And Link's character is definitely not gender-exclusive by any means. I know plenty more adventurous girls than I do guys anyway.

And I'm not even against a first-person Zelda... Metroid Prime made a believer out of me that adventure can work beautifully from that view-point.