Alright, I pointed out a number of interesting things in the trailer.
At 0:30 when they showed the bad guys, the fellow all the way to the left looked very much like Ghirahim. The fellow in the middle with the weird volcano-like head is probably his "Master." Although this legend is starting to sway me from the idea of them being part of the Dark Interlopers, I'm thinking they're their own organization that's never been mentioned until now.
And then for more obvious stuff. The speaker I'm thinking is Fi. She seems to do the random babbling like what Midna used to do. Her knowledge of all of this is quite obvious; you see the Goddess holding the Lyre that Link will be using, but also a sword. This sword, pointed Skyward, I'm almost certain is the Skyward Sword.
But now we have a few answered questions. The Triforce is obvious the powerful item that the Goddess put on Skyloft alongside the residents. Skyloft is created by the Goddess, which would easily explain how it floats, other than Nintendo logic.
This is definitely a very nice intro, and although I haven't felt really excited like a lot of members here, this is starting to make me very excited.