I... really don't think Midna can be the Master Sword. she might be. she might not be. but i don't think it's very likely that she's the master sword.

Midna, from everything i've read in interviews and general information on the game, is apparently a denizen of the Twilight, and apparently has her own evil/semi-evil agenda but teams up with Link, for her own gain.

so how can an evil/semi evil being of the twilight be such a holy relic as the Master Sword? the Master Sword was forged to destroy evil, not become it. this isn't SoulCalibur, people. Link was IN SCII, but only out of a special cameo thing. his presence in SC doesn't do anything to the Zelda storyline.

but other than that, i think Hookshot, even though not confirmed, is still going to be in the game. i'd especially like to see the Hookshot gain the grappling hook's abilities, where you can lock the chain in place to swing across longer gaps.
and Bombs. you gotta have bombs. can't have Zelda without bombs. unless you're playing Zelda 2, but that's beside the point.