Okay, I’m halfway through the book, and here’s my most recent theory:
Harry is falling in love with Ginny, throughout the first half of the book. Well, I think Harry is going to just keep getting more and more obsessed with Ginny, and worried about her (y’know, with all the disappearances, and all the danger now that Voldemort is loose), and eventually he’ll just kinda flip out, and go make a deal with Voldemort to protect her.
But, of course, Dumbledore is watching closely, so he’ll confront Harry about it, and Harry will get really angry (like he did in book 5), and then Ginny will show up to tell him he’s being a total prat and he should be nice to Dumbledore, and Harry will totally lash out at her, and accidentally hex her, and then Dumbledore will try to restrain him and they’ll end up fighting all over this abandoned lava world until Dumbledore finally wins and leaves Harry for dead.
But then Voldemort’s drones will rescue Harry and put him back together. He’ll survive, of course, but…corrupted. More machine than man….
And then he’ll kill off all the Jedi.