What now for Jamie?
Okay, he's left Cersei and is heading North to join Jon and Dany.
Is anyone in their camp going to have the brains to point out that now that he's officially out of the kingsguard, he can claim the Westerlands as his birthright? And that doing so would cut out a good chunk of Cersei's supporters, and throw many more into conflict that would leave them unable to come to her aid? Okay, Tyrion has the brains but he wants the Lannister lands for himself, and he's not going to want to push Jamie's claim. Maybe Sansa will bring it up, she'll always be looking for ways to keep Cersei a minimal threat.
One possible end game is one I hadn't thought of, but that someone on another board suggested. If neither Jon, Dany, nor Cersei survives the long's night... he's about the only person left with any claim to be any recent monarch's heir. He could be king, and marry Brienne, and she'd be there to tell him what the right thing to do would be, not that he'd always do the right thing.