So here is my theory for the ending:

It involves the three heads of the dragon prophecy.

We have always assumed that there would be three riders working together, so . . . Dany, Jon, and Tyrion. However, I believe this is foreshadowing another conflict. I believe that Dany is becoming cruel and unmanageable. While she still claims to serve the common people, in reality, her conversations center around the Iron Throne. Jon will notice this. I believe that Jon and Dany will first become first allies (against the WW), but ultimately, Dany's successes will cause her to overstep boundaries.

Jon will be the second rider and will OPPOSE Dany, not be aligned with her. He wants to protect the North and they want to be free of the Seven Kingdoms.

The third rider will be a White Walker. I believe the Night King was originally a Stark and, as such, has the power to warg. Thusly, one of the dragons will be fighting for the White Walkers a...