
1. Christian goes back to being human. No idea about the how and when, but it's a definite possibility.
2. Christian becomes the Unseelie king.
3. Dani gets trapped in Faery and grows up by at least two-three years. See comment #1.
4. Dancer gets killed and either stays dead or gets transformed by Ryodan into whatever he is. This one I'm almost positive about, and here's the proof:
"You’re going to get the boy killed one day, Dani," Ryodan says behind me.
"Rot in purgatory, dude. Batman never dies. Dancer won’t either." - Iced
If that ain't some serious foreshadowing, I don't know what is.