With Dany having a massive fleet now with the Masters' former fleet and the Iron Islands 'best ships', two huge armies with the Unsullied and Dothraki, and 3 massive dragons, the question becomes how is she possibly going to lose when she steps on the shores of Westeros? Even the White Walkers seemingly have no chance with 3 dragons who can just hover above them and reign fire upon them.
So there needs to be some twist involved right? Maybe the White Walkers can shoot ice? Or Dany needs to take that evil turn that she seemed to be taking until Tyrion talked her out of it (maybe Tyrion dies in a battle to come, so there is no one to prevent Dany from going mad?). Or the show goes to the books and...
But it seems like Dany is a steamroller at the moment.