What I hope will happen 
Dumbledore will find someway of overcoming his predicament (!) Of course, he can still direct Harry from his portrait in his office but if Harry won't be there it won't do him a lot of good.
Harry will find a way of regenerating his mother and father and Sirius. Time-turner perhaps?
Severus Snape will make good his boast of being able to 'put a stopper in death' (PS) with regard to Dumbledore.
Lupin and Tonks will marry after Lupin has seen off Fenrir with the help of Wormtail and his silver hand (maybe).
Malfoy will eat dirt permanent.
Griffindor, Hufflepuff and Ravenclaw will combine forces with Harry against Voldemort and Slitherin and clean up the planet permanently.
Voldemort will get wopped without anyone else getting hurt.
Ron and Hermione will be a serious item and will risk life and limb to save Harry. They will name their first child Harry Potter Weasley.
Harry and Ginny will 'ride off into the sunset' at the end.
What I think will happen:Dumbledore has gone for good.
The only way Harry can meet his parents is to go where they are since Jo has made it abundantly clear Lily and James can't come to were he is, therefore Harry will die. That way he can meet up with Sirius too so everyone but Ron, Hermione and Ginny will be happy, unless they cop it too in which case everybody (well, nearly everybody including me) will be happy.
Draco will die mostly because he's a coward and nobody but Pansy Parkinson and his mother like him. His father doesn't seem that keen. This does, however, make a big hole in another of my theories as Harry will also have to put up with him for Eternity as well. Unless, of course, there is a Wizard Heaven and Hell but perhaps that is a bit heavy for a Harry Potter novel. Still, anyone who can invent Quiddich should be able to figure that one out.
Lucius will reappear and die doing something horrible.
I can't decide yet which side Snape is on. I tend toward the 'good guy' side. Whatever, his role will be pivotal. He owes Sirius a favour anyway (saving his life from a rampant Lupin - don't know if that cancels out James being a prat). He might save Harry for Lily's sake - she defended him publicly against James in the pensieve. Also, he made the correct concoction for Lupin at the full moon and swapped the Veritaserum for something else for Harry in OOTP. I also agree that pleading is not Dumbledore's MO with regards to his own death - he is far more likely to plead on someone else's behalf. As Harry is the 'light of his life', I would guess it would be him.
Further to the above paragraph, Snape will save Harry at the risk of his own life.
Whatever else happens, one thing is clear - there will be an EX-VOLDEMORT!!!! If not, Jo can always write another series beginning 'The Heir of Voldemort and the ....' then everyone will be happy (with the possible exception of Harry).
