If global warming doesn't sit on the Iron Throne at the end of this, I don't think it'll be one of the main players (If GRRM gets to pick). Maybe the most fitting would be (and this has been theorized by other people) is Ser Friendzone himself, Jorah Mormont.
Clearly, they've kept Jorah around so long for a reason, and he's probably going to play a significant part of the end of her story, no? She's not into him, yet he's still kicking around.
This theory about Jorah Mormont would make an amazing Game of Thrones movie
It has been pointed out elsewhere that Jorah does fit 'has the blood of a dragon'. One being the grayscale, which kind of just exists in the plotline for padding right now, the other being his sword (Jamie also fits with regards to his sword). I don't like to give Game/Film Theorists too much credit, they primarily just signal boost theories they find on message boards and subreddits.