Pure idle speculation on my part
More of the Ron Weasley prophecies coming true - boy can see the future, despite his hatred for Sybil Trelawney's class. (So far, he's been a prefect and he's won the Quidditch cup - "Weasley is Our King". He'll probably end up as Head Boy.) The co-teaching of the class with Firenze might have somethig to do with that. He'll probably surprise himself by getting very high marks in Divination.
Confrontation between Voldemort and Harry in the air. it's possibly the only place for a wizard fight that JK hasn't explored. Harry's now coming into his powers and for the final confrontation to be anything more than a fluke, he's going to have to confront Voldemort in one sphere where he's not at a horrible disadvantage. Before the final confrontation, I mean.
* /me puts onhis robe and wizard hat*
More Malfoy pwnage is always good, but at some point, Draco and Harry may need to come to some sort of understanding. They will work together, but not like each other - kinda like Snape and Sirius used to be. Probably because Voldemort will kill Narcissa or Lucious. Plus Malfoy likes prestige - Lucious is now a felon and convicted Azkabanite so...
I don't want to see it, but the big death this rounds is actually going to be a Weasley (Bill or Charlie), Snape, Dumbledore, or even Aunt Petunia (don't laugh - she's the last living Potter relative of the blood)
The continuong evolution of Harry Potter, Ronald Weasley and Neville Longbottom as kickass instinctive wizards. Hermione is already the brightest wizard of her generation - once she remembers she IS a witch. I'm sorta tying this in with the Weasley gift for prophecy.
Heh. Some unconventional answers, eh?