No spoilers or rumors, just my own thoughts.
Only five days to go until Book 7 is finally here! Squee!
A fair amount of these are copy-and-pasted from previous posts I've made, some with alterations to take HBP into account. Some, mainly toward the end of the list, are brand-new, though.
Old thoughts culled from these two posts:
1.
Prediction list from HBP, with post-book-release accuracy results2.
Pre-HBP list of questions PREDICTIONS FOR BOOK 7:
1. A Weasley will die, but not Molly, Bill, Ron or Ginny. My current best guess is Charlie. Next most likely are Arthur and Percy.
2. Lucius will die. Narcissa, I'm not sure about.
3. Snape will be redeemed but will die.
4. Neville will avenge his parents. Bellatrix will die.
5. We will see the Chamber of Secrets again.
6. Lockhart will appear again.
7. Percy will return to the Weasley fold.
8. Luna will be proven right about one of those crazy stories in the Quibbler that she unquestioningly believes.
9. Peter will do something to at least partially redeem himself (his life debt to Harry from PoA will come into play), and then die.
10. Sirius will communicate from beyond the Veil somehow. Possibly through those mirrors that that idiot kid Harry never used. He might somehow help to pull Voldemort through from the Other Side.
11. The fact that wizards can't Apparate/Disapparate from within Hogwarts yet house elves can will become significant.
12. Umbridge and Grawp must die. Well, okay, that's more wishful thinking than a prediction. ;)
13. A Slytherin student will be a useful good guy. If this doesn't happen I will scream.
14. We will have a detailed explanation of exactly what happened the night Harry's parents were killed, who was where, when they were there, why, etc. (Please please please!)
15. We'll finally learn what the @#$&* is so significant about Lily and Harry's green eyes.
16. We'll finally learn what the deal is with Petunia and how much she knows.
17. Harry will have to face Dementors again.
18. We'll learn why Dumbledore's eyes showed that "gleam of something like triumph" or whatever it was late in GoF when he was told about the graveyard events.
19. We'll learn more about the Hogwarts Founders.
20. We'll find out that Snape was fond of Lily Evans. Whether it was just admiration or all-out luuuuuuuuuurve, we shall see.
21. The Malfoy estate's proximity to Stonehenge will come into play.
22. Godric's sword will end up in Harry's hands again.
23. Harry will make some sort of journey into the underworld. I'm not sure what form it will take, but it may involve the Veil. I do NOT, however, think he will die and stay dead.
24. Voldemort will lose. Exactly how, or even whether he finally, once and for all, DIES, is up for debate.
25. Harry's Quidditch skills will come in handy in battle, sort of like they did with the dragons in GoF.
26. At least one Death Eater (besides Snape) will defect to the good side.
27. Someone from Harry's generation will become an Animagus.
28. We'll learn Snape's patronus and boggart and it will be really cool.
29. Time travel as a plot device will show up again.
30. A Hogwarts professor will be revealed to have an oh-so-secret family (spouse and/or kids) because JKR hinted at it once
31. Mundungus Fletcher will show up again and will meet a bad end.
32. Remus Lupin's fate...I don't know, I'd say he's got a 50/50 shot at living to the end. I can see JKR wanting to make a clean slate and killing off all the Marauders, or I can see her leaving him alive as one last link to Harry's parents.
33. Dumbledore's portrait will give valuable advice
34. It recently came to light that the moviemakers were planning on leaving Kreacher out of the OotP movie but JKR told them they'd regret it later if they did. Thus we can assume the wrinkled old monster will have a role in book 7. My guess is that he has a Horcrux stashed away in all those Black family mementos he refuses to get rid of.
35. Hagrid will live. Unfortunately.
36. Draco will live. I don't think he's brave enough to actively defect from the Death Eaters but I think there will come a time when he chooses to look the other way, not raise the alarm, etc, to help the Order somehow.
37. As much as I LOVE the "MacGonagall is evil" theory, I don't expect to see it become canon. Will she live? My hunch is yes.
38. Aberforth Dumbledore will be useful in some way.
39. Some Hogwarts professors will die. Maybe Flitwick and Sprout. If Sprout dies Neville will become the new Herbology professor.
40. Some familiar faces from the Order of the Phoenix will die. Moody and Shacklebolt, maybe.
41. Fleur and Bill will get married and live.
42. I don't know if it'll actually happen, but I'd love for Harry to address Voldemort as "Tom" at some point. I loved that part in OotP where Dumbledore did that, and I think it would really show Harry's superiority over Voldiepants.
43. Hogwarts will be open during Year 7 but the Trio won't spend much time there. They'll probably have to do research in the Restricted Section of the library.
44. Ron and Hermione will be a couple.
45. It will be clearly implied that Harry and Ginny will be a couple in the near future but I don't foresee a proposal or anything really concrete during the main action of the book.
And some more questions (mainly culled from the second link above)...
Why did Snape become a Death Eater in the first place?
What did he do to earn Dumbledore's trust so completely?
If Dumbledore is so wise, why didn't he see through Lockhart's lies? If he did, why did he hire him?
What the hell is that Veil, anyway? Shouldn't there be a guard rail around it or something? o_0
What, besides time, made James Potter mature enough to win Lily's heart?
Did Snape love Lily? If so, did she know? Did she love him back? If so, what drove her to James' arms instead?
What were the other two memories Snape put into the Pensieve besides his "worst" one?
What made that his "worst" memory? The humiliation? Alienating Lily?
Are we correct in assuming the "hook-nosed man" and the woman he was yelling at are indeed Snape's parents? Or are we reading too much into what Harry was seeing in that glimpse of Snape's memories?
Whatever happened to Snape's parents? Did one of them kill the other? Are either of them still alive?
Is Snape an only child?
What happened to Lily's parents?
Is Dumbledore's the only Pensieve in the world? How common are they?
Will Wormtail do to Voldemort what Wormtounge did to Saruman?
Will the enchanted Ford Anglia ever show up again?
Isn't anyone a little concerned that the centaurs in the Forbidden Forest are, like, on the warpath and stuff?
What the hell is Grawp doing? o_0
Will Trelawney come up with more bonafide predictions?
What's the story with the rest of the Hogwarts ghosts? We only really "know" Nearly-Headless Nick and Moaning Myrtle. What about the others, especially the Bloody Baron?
What else is in the Department of Mysteries?
How will Lucius and the other Death Eaters get out of Azkaban? Will they?
Are there any long-lost relatives of any major characters lurking out there, or is that too cliche?
Are Hedwig, Pigwidgeon, Trevor, Crookshanks, Nagini and/or Fawkes really animals, or are any of them "pulling a Scabbers"? Would JKR be lazy enough to do that again? I lean toward not, but you never know...
What will the trio do as careers when they graduate from Hogwarts? Assuming they all survive, that is.
Since Hogwarts is in Scotland, can't we PLEASE have a Loch Ness Monster reference or two? Pretty please?
Will we ever meet Tonks' parents?
What did Dudley see that upset him so much when the Dementors attacked in OotP?
I'll edit later as I think of more things. ;)