The Slavers will be destroyed by the action of Barristan, Tyrion and Victarion; Barristan dies, Vic tries to control the dragons with the horn and dies in the most ridiculous and epic way possible at the same time.
Dany gains fastly the support of all the dothraki with the help of Drogon who will burn all the khal, she control them either by fear or devotion, probably both. Then she wreck havok on Yunkai and come to Meeren and make Tyrion her first adviser according to his knowledge about the Lannister strenght and weakness, she promised him Castlery Rock but stays very careful about him, she slowly turn into an implacable despote and move to Westeros with the rest of Slavers and Ironborn's fleet.
Stannis fight bravely the Bolton and force them to retreat a first time, the siege begins but last very long. Shireen will be burned at one point. Liked it or not, but I am pretty sure he will die the same way than in the show, alone, sad, disillusioned by his destiny and killed by Brienne when she will be in the North to deliver Robb testament by order of LS.
Rickon comes back from Skagos and stay prince after the revelation of Robb last will.
I can't imagine what will happen to the Greyjoy siblings but the thing I am sure it's that Theon will survive the book, after all the hell he went through, why kill him now ? He has to pay the iron price protecting Winterfell and the two youngest Stark when the dead will come in ADOS.
The Wall and beyond
Jon will come back to life with the help of Melisandre in fire and smoke. He kills the traitor and leaves the NW because his watch ended when he dies. He comes to the North hoping he will help Stannis with the free folk but ending the conflict becoming the leader of Stannis army and retake Winterfell with the major help of the Vale and Sansa.
The march of the death begins, they took millennia to rebuilt their army, killing wildlings and the NW every now and then (they are for sure the most perseverant players in the game) but now they are ready. The Hold the Door chapter will be awesome, everybody in Bran's group dies and he escape with the help of Coldhands. Bran's vision will help us to learn a lot about a lot of things.
Sansa become as strategic and machiavelique as LF. Robin dies, Harold too after the wedding. LF want to rule the North and the Vale with Sansa, he become the lord of the Vale and marry Sansa (many lords of the Vale will dies by "accident" to limit and prevent the opposition). They will retake Winterfell with Jon and the shit will begins when they will learn the last will of Robb about the North.
LS will pardon Jaime and Brienne in one condition. Jaime has to help the BwB in the fall of house Frey, second red wedding is coming. Brienne will have to go to the North to keep her oath and help her daughter to retake her home and in the same time, to prove the veracity of Robb testament and make Jon king in the North, she kills Stannis at some point.
Knowing that Robb was avanged and his last will was finally respected (Jon will be King of the North at the end of the book), she will be ready to go. Arya will leave Bravos and stop in the Riverland at the end of the book, she will be the one to put an end to Cat's second life and giving her the peace she needed.
Before this, she will meet a lot of old comrades, helping her to understand she never was no one, but always a Stark from Winterfell : Nymeria and her pack, Gendry with the BwB and maybe the Hound who will come out of his retirement for some reason.
Faegon's Invasion/KL Stormlands and Dorne
Cersei become Mad Queen and killing everyone using wildfire is a pretty good climax for me (she will do what Jaime stopped in the past with Aerys, there is no way he stay with her after that). Furthermore, I think Marg and the High Sparrow have to go to clear the way, because Cersei will be a better opposant for Faegon-Dorne and/or Dany. More irresponsable, more dangerous, more disturbed and capable of heihtened tension in the most dramatic way.
Faegon take SL very easily, no major battle with the Tyrell force because they will rally with him to try to defeat both Euron and Cersei. Doran will want to assure his place of power and get Dany out of the game before her arrival. When Dany comes, she organize the alliance with Faegon and the war by trying to save the population of the 7K and KL by not using dragon on the cities but become mad when she learns the Martell and Faegon want to get her out of the game. Faegon is a blackfyre, along with Ilyrio and maybe Varys. They don't want to be the minions of the Targaryen Queen, and Doran want a bigger place in the 7K and want to see the Martell into the royal family just like he wanted with Elia. And of course, he can't forget Quentyn's death by Dany's dragons and judge her accountable as much as the Lannister are for Elia and Oberyn. Shit goes wrong. Dany burns Sunspear and the Water Garden. Drogon kills Illyrio and maybe Varys.
In the same time, Faegon will have to order the execution of JonCon because he can't save him and he contaminated a major part of the GC but enters in conflict with the Ironborn and dies by the hand of Euron. I can imagine a scene where Euron looking at JonCon using the same quote than Thanos after breaking the neck of the false dragon: "NO RESURECTION THIS TIME ". Yes it's another level of fanfiction lol but the level of epicness would be something.
I don't see Hotah dies but he will stay out of the major conflict for the major part of book, his hunt of Darkstar leads him and Obara to Starfall and his POV will help the readers to learn a lot of stuff about Ashara, Dawn...
A god damn lot of magic and mystic stuff happens leading him to provoke the death oh his brothers, destroying the citadel, killing Faegon, gaining the control of the GC (now composed in a major part of stonemen); he takes the winter horn, tames one the dragon with the help of Jaquen h'ghar and destroy the wall. He is a fallen potential 3eyed raven but now just the one Crow's eye, (like a padawan turning into a sith instead of a jedi), an agent of the chaos, the last storm who will make a clean sweep of the 7K to build something else; something better to him. End of TWOW.
Yes, TWOW has to be at least a 1500 page book. At least.