The Iron Born could be the second coming of Lord Nelson! It doesn’t matter, Dani has a Naval air arm that no one else has or can successfully defend against called dragons.
My only guess is Euron Greyjoy will use the horn Dragonbinder to control one or more of Dani’s dragons. You know, the only plot device capable of removing Dani’s OP advantage because...drama. No one really cares about the fight for King’s Landing. We just want the Night King to get move on down south.
I’m still wondering how the Lannister’s are paying and feeding their troops. They ran out of gold seasons ago and the best farmlands have revolted.