Speculation time:
Melisandre heads south and meets up with Bwob, turns around and heads north.
Arya heads south to cross the last name off her list, cersei, but runs into bwob, fulfills Mel's prophecy. "I see death in you, we will meet again."
Arya stealth kills Mel, but the hound is blamed so he jets before they can hang him, and arya and bwob continues with bwob to the north for reunion with Jon and sansa.
Dany arrives within the first few episodes, landing in the storm lands, meeting up with dornish and reach armies. They prepare to march on KL.
Cersei can't handle the walls closing in and plans to burn down KL, Jaime ends up killing cersei, but before that can happen, the hound arrives and Jaime + hound defeat the mountain, enabling Jaime to strangle cersei to death before collapsing from his own wounds and dying. An injured hound is the only survivor and takes off to be a peaceful Shepherd/gravedigger etc.
Dany simply claims the throne, her forces are too massive for anyone to contest her. Tyrion inherits command of casterly rock/lannister forces.
Meanwhile in the north, LF plots to divide Jon and sansa, and it's presented as sansa is in board with His plan, but really she betrays and murders lf, student has become the master scenario, she plays Robin has him wrapped around her little finger (lol pun) and basically controls the Vale.
As this is happening, bran arrives at winterfell to reveal what's going on beyond the wall, and the nk breaks the wall somehow and the wall comes down and the dead with them.
San finds some old book that explains something important about who the nk is and how to defeat him. He heads to KL to speak with the new queen and get her support, at the same time word comes from winterfell that the army of the dead is basically marching on winterfell, they are asking for help from all the realm.
Dany and co, including all the southern armies march north.
That's my season 7 prediction, the last scene being the army of the dead completely surrounding winterfel like a siege, but war z style mountains of dead climbing the walls