i think he’s already changed everything he can change, as it were. I don’t think there’s going to be any plot-changes via time-travel. But things he’s already set in motion paying out? Sure.
One possibility people have been talking about for a long time is that he’s the one who made Aerys mad, and filled the city with Wildfire because it’s going to get used in some sort of apocalyptic final battle in King’s Landing. Potentially Jon or Dany could survive being in the city when it went up too, if either is still alive at that point.
EIther way I don’t think the Chekov’s Gun of the Wildfire that is spread through King’s Landing is going to get ignored. The Night King will reach King’s Landing, and it will go up, quite likely with him in it. And indeed possibly most of the characters.
The trouble is for theories now, of course, is how short the timeframe is. Two more books could have a zillion things happen, but five episodes? I am pretty sure King’s Landing will blow in the last episode or so, but beyond that it’s going to be a theory bloodbath. Time for final predictions?
Robert Strong/The Mountain killing Cersei seems like a lock-in
Qyburn betraying Cersei also seems very likely
Bronn is unlikely to kill either Lannister brother given the vague promises made to him
Arya wouldn’t have a Valyrian steel dagger if she wasn’t going to stab some fairly major undead, though who that is I dunno
Gendry is the only character I can honestly feel is more than 50/50 likely to be alive at the end of the show
Dany I am quite certain will die. Probably heroically.
People have suggested Cersei and Dany are pregnant. I suspect neither is, but, if they are, I expect we’ll see some kind of hold-up, perhaps holding the Night King at the Twins, that allows both to give birth, and various machinations so that by the end, a blond-haired child survives but we don’t know which of them in belongs to. This is an ultra-long-shot I am admit but hey…
If she doesn’t die heroically in dragon-back battle, I fully expect someone like Sam, quite possibly him, to kill her. He could very well do so after they defeat the NK, too, if it looks like she’s going to become ruler of the Seven Kingdoms, because he is definitely not down with her ruling style, and is all about Jon taking over.