Originally Posted by 8 Ball
It's not going to be Euron, his story lies elsewhere. He's going to be involved with Vic and Dany, possibly even shit to do with The Others. He's sailed all across the world, been as far as Asshai and he's been to the smoking ruins of Valyria, where no other man has walked. He knows a lot of shit, he's gonna be tied in with the mythical side of the story. It wouldn't be fitting for him to kill Cersei.
The valonqar has to be either Jaime or Tyrion. Jaime would be much more satisfying though. The only other possible valonqar who isn't Jaime or Tyrion and who would be fitting and satisfying enough would be Stannis. But I don't think we're ever going to see Stannis back in the South or Kings Landing. His fate is in the North.
Isn't this exactly the kind of unpredictable twist Martin would do? But, yeah Euron is related to mythical side of story. he is awesome though. Victarion is my favorite Greyjoy after Theon. Most reader find Damphair chapters boring, but i like him too. I like his 'I must suffer for the better of my people' attitude.
speaking of Stannis fate being in the north, I would not be surprised, if he become Night king. John Snow becoming Night king would be crazy too. that would probably be first time in fantasy that supposed Hero turn into heel(That if others are indeed bad not dragons).