Once again I need to remind everyone, the only reason Galaxy had orchestrated music is because it's composer, Mahito Yokota wanted it. It's the composer of the games who decide what kind of music they wanted and most Nintendo composers are fine with MIDI.
So I'm going to outright say it right now since this is what this orchestra argument always leads to, unless Yokata is working on Zelda Wii's soundtrack, it's going to be MIDI. And since Yokata is Tokyo EAD's head composer, and Zelda Wii is being made by EAD 3, who's head composer is TĹŤru Minegishi, I don't think Yokata's going to be involved.
So I suggest people wanting Zelda Wii to have orchestrated music take out all your rage right now so E3 won't be a big shock.