Okay, so here's what I've gotten from watching the trailer a few times.
Ganondorf's real body is in a cave/dungeon underground. It has a disembodied white glowing arm attatched to its chest and Ganon is basically a lifeless mummy. Magical energy is swirly around the arm. The energy looks like Gerudo language. Something happens where malice comes in and it looks like Ganon's body revives.
It seems like the arm may be an ally. At one point there is a flash of lightning and the shadow cast on the cave wall looks like a flashback to the past where someone attacked and defeated Ganondorf. I think you can see the figure the arm belongs to:
Maybe a monk?
The arm reaches out and saves Link or Zelda from falling.
At the very end, Hyrule Castle begins turning into a new Skyloft.
So my interpretation so far is this:
10,000 years ago someone, maybe a monk, helped seal Ganondorf's body away and their arm is all that's left. Link and Zelda enter the temple and find that the seal is almost gone. Ganon's malice enters and drives away the arm and revives Ganondorf. Link and Zelda fall and the glowing white arm saves them. Then Hyrule rises to the heavens.