I'm pretty confident that Bronn is gonna take his miniature cross bow and bring down Drogon. He missed his chance the first time. Now he will get a second chance with an even smaller bow. He's gonna save Tyrion once again when the Mad Queen tries to execute him for betraying her. That is why Drogon went on a rampage. They're building the moment up so we can all be like, "OMFG BRONN KILLED DROGON WITH A TINY ASS BOW." And at that point no one will care as much either because she just used Drogon to kill millions of innocent people. Dany might die too. Then perhaps Jon will take the throne.
he'll point the bow all the way from Winterfell at the start of the episode. The episode will carry on as normal. In the final moments of the battle we'll get a x-ray shot of the arrow expertly going through the mouth and exploding the heart.