In the end we will learn that this entire series has been nothing more than a protracted nightmare in our hero's mind. He finally realizes that he is only dreaming and decides that it is pointless to continue with this reverie, so he rushes through the last bit skipping over most of the important points. He briefly wakes, only to discover that he is still full of arrows -- that part *wasn't* a dream. Boromir dies, and we never do find out what happened to that damn ring.
No one will sit on the iron throne since it didn't survive Drogon.
Dany will commit suicide by dragon after she realizes what she has done.
Drogon will go back to Valeria where he belongs.
Gregor the indestructible will arise from the ashes and kill everyone else.
The show will end with Bran sitting in the godswood and given a boring monologue which tries to tie up all the loose ends which would have been tied up properly if some idiot at HBO hadn't tried to condense what should have been 3 seasons into 6 episodes.