Fuck it. This is how I would have liked it to play out:
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At end of series six all seven rulers would have met and decided to send their armies north to face the Night King. Tyrion convinces Cersei that they are the last of the Lannisters and it's the right thing to do. She reluctantly agrees that there's no point in having the crown when her children are dead.
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Cersei then finds out she's pregnant so decides to hang on to the crown for her son. She also looks at a map of Westeros and correctly deduces that the North is massive and will be overrun and the only place to stop the army of the dead is the Neck. (Think Thermopylae with flaming peat bogs). She decides to cut the North loose (correctly figuring they will refuse to abandon their lands) and tells Jaime to fortify the Twins and prevent the other five armies marching north as they'll be needed to defend the Neck.
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Night King really starts to fuck shit up in the north. Danaerys realises her advisers are idiots, have fucked it up and they are trapped. She flies south to convince Cersei to let reinforcements go north.
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Cersei barricades population in Kings Landing and tells Dany that she's put wildfire all around the city and one spark from Drogon will create a Dresden fire storm. Cersei plays on Dany's mad daddy issues about burning the city and mocks Dany that the North is fucked and her army is about to be wiped out. Dany has moral quandary - destroy Kings Landing or everyone in the north dies. So she incinerates Cersei and in doing so the entire city goes up.
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Dany then confronts Jamie who bends the knee. But he then explains again how strategically the North is already fucked and should be abandoned (he can call back to how he abandoned Casterly Rock to show he actually understands this). Dany realises Cersei was actually right after all and she should have listened to her. She then flies North and pulls her armies out.
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Night King overruns the North but gets stuck at the Neck due to flaming peat bogs and flaming dragons. Meanwhile Bran (who I would have left in his cave) works out how to use his tree network and warg skills to provide real time communication allowing various raids to kill each of the white walkers. Each one killed takes out 10% or so of the army of the dead. Move the Hodor scene here - once the Night King works out who is coordinating the attacks he can assault the cave and Hodor can have a more meaningful end.
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Night King gets desperate as his army is destroyed and decides himself to force through the Neck and is defeated (don't really care how or by who).
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Cue big celebration at Winterfell to celebrate the victory (also J+D wedding perhaps?). Jon tells Sansa how she reminds him of Ned. Sansa comments that her mother taught her some lessons too. She then orders repeat of Red Wedding and Dany, Unsullied and Dothraki are all killed. Jon goes for Sansa. Arya sticks him with the pointy end. Sansa makes the point that Dany's decisions killed entire population of Kings Landing and the North so had it coming.
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Sansa is Queen in North. She tells the other kingdoms all to fuck off and rebuilds the wall on her southern border (got to stop all the other kingdoms sending their rapers and murderers across the border...).
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Final shot - iron throne is abandoned in the ruins of the Red Keep.