Link's appearance seems to be a mix of Ocarina of Time (adult) Link, Twilight Princess Link, and Skyward Sword Link. Still, it is clear the vibe of the design seems to be from that Zelda Wii U Tech Demo, which is probably what Link on Zelda Wii U is gonna look like.
I wouldn't be surprised if Zelda got a similar treatment, although her Skyward Sword outfit would be a nice touch. However, Zelda's Twilight Princess redesign has gotten better fanfare than Link's, especially since a lot of people felt her blonde hair looked kinda weird in Ocarina of Time and Melee (it was just too bright and blonde, lol!!!).
As for Sheik, I'd rather go for some Melee-Brawl design hybrid. I like the "edgy" feel of the Brawl design, but I just love the classic "look" and "feel" so much from Ocarina of Time. Finding that right medium for the design of Sheik's outfit(s) would be so freaking rad to see.