Just finished 76. This might be crazy, but...

I predict that Harry just went Dark. He discovered that wizards can be imprisoned without torturing them to death via Dementors, and yet people still tolerate Azkaban. The majority of the adult wizarding world has now given up their right to moral consideration in his eyes, a simple extension of the Death Eater: "His life is already bought and paid for, then, and I can do anything I want to him without ethical problems."

Unless something drastic changes his course, he will impose his will upon the wizarding world by force and remove the moral atrocity that is Azkaban.

Further speculation - that "something drastic" is Harry himself. Somehow Hermione ends up dead due to his actions. He develops a way to travel much further into the past than a mere six hours (possibly sacrificing the whole world, won't much matter if it's going to be disappeared into an unstable time loop anyway) so he can change the past. The story we're reading is the "second" run through of events (yes, technically there's only one, the lack of Time Travel English Vocabulary fails me), Mr Hat-and-Cloak is Future Harry, and he's meddling with everything to prevent First Harry from going Dark. Or, if that fails, trying to get Hermione out of the path of danger by getting her to leave the school and/or stop trusting First Harry.