I reckon it might be GENDRY (should it turn out that he really is the "black-haired beauty" child of Cersei and Robert Baratheon)... Else, THEON GREYJOY (because, in the Game of Thrones, anything could happen, could it not?).
I'm with Levity, I think the throne is gonna get destroyed. Symbolic bleh bleh, uniting bleh bleh, etc.
Iron Throne gets destroyed, no one gets to rule as a king/queen and democracy gets introduced to Westeros. Or Jon Snow aka my boi Aegon, he's been through so much shh and everyone is always giving him shh. Like he deserves to live out rest of his life as a King.