Listen to the music in the trailer backward, as captured by WiiC24, and you'll hear the Hyrule Castle Theme from Link to the Past. Check it out in the video above; the old theme is here:
This isn't the first time Nintendo has flipped past Zelda themes: They reversed Zelda's Lullaby from Oarina of Time to make the Ballad of the Goddess in Skyward Sword:
Goes to show, if you write enough good melodies, you can always go back to your past works, flip them around, and get a whole new collection of tunes. Feels like there's a pretty good Nintendo joke to be made here...