WELL, since it's completely off the rails:
Jaime and Bronn would meet up en route north, and together would recruit the Tully army, taking them along. The Northern lords would go off to rally their troops, except the Night's King would show up and that really wouldn't happen. Lyanna Mormont died on her way back to Bear Island, etc. Everyone evacuates Winterfell, and eventually make their way south, with the idea, at Tyrion's suggestion, to make their way to the Eyrie for their last stand. Jon would learn the truth from Howland Reed, who stays behind. Theon would be killed when Winter comes to the Iron Islands.
There's a big ass fight, where Brienne, Pod, Grey Worm and Tormund all die at the Eyire. Bran wargs into Rhaegel. Eventually they win, I forget how exactly.
Arya makes her way back to King's Landing to kill Cersei. She does this by killing Qyburn and wearing his face.
Dany becomes pregnant and rests at Dragonstone. Shortly after giving birth to a daughter (that she names Lyanna), the baby is whisked away to safety by Varys as Euron takes over the Iron Throne, and shortly after birth Cersei's troops storm Dragonstone, with Jorah dying as he tries to defend her. Dany dies shortly after, and her body is displayed in King's Landing.
Jon begins riding Drogon, fucking some shit up, Eventually in King's Landing, everything comes to a head as the Hound fights The Mountain, pushing his face into a burning brazier, and Euron corners Drogon and Jon in the Dragon Pit, along with Jaime (I forget what he was doing TBH). Turns out the Dragon Pit is where they stored the rest of the Wildfire. BOOM.
Three years later, Sansa rules the North and Vale, Edmure rules the Riverlands, Sam is married to Gilly and runs the Reach, Bronn marries one of Oberyn's daughter, and for some reason, Tyrion is still hand, and has hooked up with Missandei while they serve as Regents for Queen Lyanna. Davos at one point went home, and Gendry ended up married to Arya.