In the preview for next week, Dany says, "the dead are already here." Everyone assumes she is talking about the bodies in the crypts, but I propose she is talking about Jon Snow. He already died, and just as that death released him from the Knight's Watch, I think she'll make the claim that his prior death also forfeits him the Iron Throne.
Also, another theory I haven't heard. When Danny and Jon have their intimate moment by the waterfall last week, the dragons looked on like peeping-Toms. What if that was really Bran Stark warging into a dragon to keep tabs on them? It might explain the stupid look on the dragon's face.
Finally, Arya now knows Gendry is Robert's bastard. They don't drop that nugget without some endgame in sight. Could she still his face to take his "rightful" place on the Iron Throne?