Yara regroups and builds a large navy (because apparently people spawn as adults in Westeros) which takes Euron by surprise when he tries to shoot down Dany again.
Dany, thankful that Yara saved her remaining army from certain destruction, decides to go lesbian and ditch Jon Snow. They sail off into the sunset while an epic boat sex scene occurs and leave Jon to figure out how to defeat Cersei.
Jon loses the battle because he can't plan for ****. Arya steals Ser Pounce's face and swipes at Cersei; the scratch becomes infected and Cersei dies. Gendry becomes the king of the 7 kingdoms and the new Ser Friendzone as Arya rejects his marriage proposals every month.
The end.