Season 11 (the true final season)

Jon explores the lands beyond Asshai to find more dragons to prepare for the final war against the Night King, now Euron Greyjoy, as well as the war with undead Dany who now seeks vengeance on Jon Snow for killing her.

Euron has regained his strength and realizes what a "*****" the previous Night King was, afraid to simply freeze the Narrow Sea to cross over into Essos. His army also starts marching south again and Twins is the first to fall. Dany's undead are simply unable to hold off superior numbers now with Euron's strength renewed.

A truce must be reached, Tyrion proposes that Jon Snow return the two dragons for temporary peace with Dany, plus alone neither side would seem capable of truly defeating the Night King. Dany doesn't have the numbers while Jon's army is vulnerable to being turned. Jorah also insists that they do not make the same mistake Cersei did when refusing to aid them. The two sides agree to a truce until the Night King is vanquished and Dany regains her dragons... which she immediately sacrifices and reanimates so they can no longer be turned.

So far the Long Night has lasted for at least 6 years and is spreading to Essos with reports of undead attacks as far as Meereen. Apparently Euron has found a way to become even stronger than the last Night King and can now raise dead from hundreds of miles away.

Dany and Jon decide they must take the fight to the Night King directly. Creating a divergence with Bran's help, they manage to gather an elite force armed with dragonglass and many dragons right outside the Night King's seat of power. Qyburn and Lyanna however betray them by launching caches of wildfire upon both living and dead. Many die, including Theon, Yara, Brienne and Jaime. Night King Euron survives but retreats. Jon and Dany's forces survive but scatter after taking many casualties. Eventually however the traitors are dealt with and Dany and Jon regain some level of trust enough to storm Euron's keep.

En elite force enters the keep during the battle to confront Euron. Tyrion who stubbornly decided to join anyway, remarks "whatever happens here will echo through the ages, they will know that we fought with honor!" It was slightly out of character for him so the group simply assumed he was kinda drunk.

Euron overpowers them and prepares to finish them off but in his vanity wants a final word with a restrained undead Dany first. Dany remarks that he forgot one of them as Arya resurfaces and stabs the Night King with dragonglass which doesn't actually kill him instantly.

In his dying state he uses the last remanents of his power to resurrect all dead across Westeros and much of Essos.

Melisandre remarks "I sensed a disturbance in the force as he went down, without their master's command, the restless dead will become an even greater threat to this world. Control must be maintained, I'm afraid there must always be... a Night King now."
Bran says "The weight of a such a burden, it must be mine, for there is no other..."
Bran is then interrupted by Dany "No, I wanted to be Queen of the Seven Kingdoms for so long I had forgotten what truly mattered. Aegon Targaryen, my nephew, he is the true heir to the Iron Throne and you are Lord Brandon Stark, Warden of the North, let this last act of service be mine. The world of the living can no longer comfort me."

Sansa looks annoyed. No lady warden of the north for her and Bran's acceptance seems to suggest that he really really doesn't want her ruling the north if he's willing to accept a title he never wanted.

As Dany ascends to her new position as Night Queen she gives everyone a final warning:

"Now, it is time for you to go. Leave this place and never return!"

Conclusion

Daenerys Stormborn continued to rule as Night Queen indefinitely, forever jailer of the dead, joined by the remaining free willed undead including Greyworm and Missandei. Jon Snow, real name Aegon Targaryen, claimed his rightful Iron Throne and married a non-Targaryen ending the cycle of incest kings and queens. The song of ice and fire had finally been played out.

Meanwhile the Night's Watch was rebuilt, mostly to keep criminals away from civilization. The Wall was rebuilt just in case Dany would ever have a change of heart and rise up against the living. Samwell Tarly however would not have to rejoin, all previous members were relieved of duty with the previous Night's Watch disbanded after having fulfilled its purpose. They could rejoin only voluntarily with a new oath. Most chose freedom.

Melisandre shattered her amulet and finally died a natural death before the break of Dawn.

Bran Stark became Warden of the North, mostly to keep Sansa away from that position of power, something Jon no longer trusted her with after seeing the naive girl he grew up with turn into Baelish II. Tyrion survived the war to become Jon's Hand of the King. Many of the refugees from Essos came back to Westeros and settled down to rebuild.

Gendry Baratheon was decreed to no longer be a bastard and became Lord of Storm's End.

Arya Stark wandered off on new adventures to Essos.

Tormund and the free folk settled in the north while the few surviving Dothraki returned to Essos wanting nothing to do with Westeros anymore after what they had just survived.

And Bronn? He long figured that it wasn't worth getting mixed up with either side. Instead of killing Tyrion or Jaime as Cersei had asked he simply decided to pull off one final heist on the Master of Coin, which as he correctly guessed Cersei was too incompetent to even suspect him of doing, took the gold and spend the remainder of his days drinking and ****ing in Dorne, a place that managed to last the Long Night without ever being breached by the dead.

The Mountain was ultimately destroyed in the final battle by Clegane who also retired in Dorne.

The End