I bet you anything he is. I can't wait for it to come out. And I wonder if that evil unicorn is coming back.
Probably not gonna happen, since Nightmare Moon was defeated and reverted back to Princess Luna.
What if the big twist is that Discord is Celestia's evil brother?
Again, I doubt it. It would be a bit too same- to give Celestia yet another evil sibling.
My bet is that Discord is some sort of dragon-like creature. Mainly because in that big picture, with the stained glass windows in the back, there are alot of pictures of one particular dragon, who apears to have, among other things, a hoofed leg, antlers and a pegasus wing. And there is that one window on the far left and the back right with what appears to be Celestia and Luna flying around the same dragon, only white.
Also, did anyone else notice the window on the far right that actually shows the Mane Six fighting Nightmare Moon? Maybe this is some sort of Hall of Prophecy or something?
And I cannot wait to see how they explain the 2 Twilights thing.