I would love to go on an adventure as Child Link once again! And it doesn't mean you can't play an adult Link in the same game, either. Time can pass for whatever story-based reason. But yeah, bring on the little guy! Link's deeds are so much more impressive when he accomplishes them as a small boy instead of a strong and capable adult. Sure, I might miss Adult Link's smexiness, but I'd give it up for epic feels any day.
However, I don't want to play Child Link in a realistic style. I don't think that means Nintendo should have to revisit the toon style, but maybe revisiting OoT's style will do just fine, especially if it's for 3DS (less work in the long run!). I feel like the world should reflect what it seems like through a child's eyes (Aonuma's words for his design choice in TWW), so the vibrant anime style of OoT could work, but then again it's better to work on new looks sometimes.
Anyway, yeah, I'd be really excited if he were to appear in ZWU. ^_^