Not the release date (last intel: not in 2018, that's all we know), but the content. What's going to happen? Who's going to die? Here are my brief guesses for some of the main characters:

Jon: Inhabits Ghost for a while after his human body's death (like Varamyr in the ADWD prologue), then gets resurrected by Melisandre. GRRM has said he always found it cheap that Gandalf returned hardly the worse for wear in LOTR, so I'm interested to see how Jon's different. In the show he seems slightly more carpe-diem, but it also seems like the show has mostly forgotten about it.

Stannis: Takes Winterfell (look up the Night Lamp theory if you're not familiar with it) from the Freys and Boltons, and holds onto it against an eventual siege by the Others.

Bran: The show has probably disproven this, but I still think he becomes a prisoner of the Others next to his uncle Benjen, because the Others can't kill a Stark for some reason.

Sansa: I think Harry the Heir turns out to be a nightmare, but Sansa learns to deal with him and use the power of the Vale to help the Starks in their fight to retake Winterfell.

Arya: I think she comes back to Winterfell and gives the gift of mercy to her mother, after seeing what she's become.

Daenerys: I think she'll have a longer experience taking over the Dothraki than in the show, and she'll fly west across Essos, laying waste to the free cities and setting the slaves free. In Westeros it will be completely unclear to everyone whether she's mad or not.

Tyrion: I think he will continue to fall into moral decay and after becoming a close advisor to Dany will encourage her "fire and blood" side. (Especially since she's his aunt!)

Theon: Something about "what is dead may never die, but rises again harder and stronger" makes me think he's coming back as a wight.

Victarion: Blows the horn and dies from it.

Cersei: I think Jaime will kill her, and fairly early on. I think Aegon will have the role she had in the most recent seasons of the show.

Jaime: I think he survives the confrontation with Lady Stoneheart and, disillusioned with both her and Cersei, leaves high society to lead the Brotherhood Without Banners.

Brienne: Someone has to die with Lady Stoneheart, right?

Aegon: I think he successfully conquers King's Landing. He'll eventually die by foolhardiness, but probably not for a while.

What do you all think? Anyone I'm forgetting?