I kind of think it will be a realistic style that harkens back to OoT's mood; not as gritty or adult as TP was, but pushing the graphical capabilities of the Wii. Just about the only complaint people had about TP's graphics were that it looked like a Gamecube game (...which it was).

Nintendo already went all-out with Metroid Prime 3 and especially Super Mario Galaxy in terms of graphics. They almost got chided for Brawl, and it looks like the same thing might happen with Mario Kart Wii, but the solid framerates of both titles keeps them held up over the criticism. I still think they're going to try to push it with Zelda, since it's their flagship franchise.

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My timeline theory:
Same sword, different day.