I’ve only read 2 books from George RR Martin but I have sufficient data from forums to state my predictions for the upcoming books. Without ado are my potential results for WInds of WInter and a Dream of Spring:
1. Jon Snow will be revealed as the son of Rhaegar Targaryen and Lyanna Stark. It will be revealed from the perspective of Bran and the godswood of Winterfell. From which Ned Stark confessed to the heart tree in prayer to keep the secret of Jon’s identity.
2. The Faceless Men initiated the Doom of Valyria.
3. Jon Snow is Azhor Azhai reborn.
4. Sandor Clegane (the Hound) will burn his brother the undead Gregor Clegane, aka the Mountain aka the Robert Strong.
5. Cersei will be choked to death by her valonqar, Jaime.
6. Jaime will choke Cersei for having killed their son Tommen, possibly in the hands of Robert Strong aka the Mountain aka Sandor Clegane.
7. Littlefinger will be killed by Arya Stark. An assassin of the faceless men, Arya will see her sister in the Vale.