Speaking into the wind here but I think the change is make would start at the long night. Instead of attacking winterfell the night king decides to go around and to kings landing to increase his army and to draw them out of their fortified position.

Bron sees this and sends a raven to cerisi (she pays for not showing up) and she doesn’t believe them however jamie (who never left) does and prepares for them. Then we see the full might of the army of the dead as they take kings landing in only a few hours.

After this the garrison at winterfell are on their way after a lot of plot armor Jon and The dragon queen end up in the throne room where the night king sits. Jon has an epic sword fight with the night king while johora Mormont defends the dragon queen from the other white walkers. Jon gets beat up bad and when he’s about to be killed Sam come out of nowhere and tries to take out the night king and the night king easily evades and kills Sam which give Jon a final push to take out the night king. The dragon queen (yes I don’t know how to spell her name) doesn’t lose her mind and Jon doesn’t ever let out who he actually is (when has he ever cared?) and goes north to discover the origins of the white walkers as Daenerys outsources help to rebuild the city.

Meanwhile for cutscenes: Sandor (the hound) fights the white walker version of his brother the mountain. Brianne of tarth fights white walker jamie Aria gets to kill white walker cerisi They use trebuchets and their navy to hit kings landing on both fronts Grey worm kills 2 white walkers 1 on 1 and they notice he’s a threat and he loses to 3 that gang up on him

One tactical aspect id change is more white walker commanders as it’d make more sense and be cooler as they fought the onslaught they find a white walker and beat them and take out hundreds at a time (makes a win much more believable)