this is what i think , well i dont think it will really happen but itbe cool if it did. draco gets his revenge on harry and goes hardcore in the next two and kills hermione and maybe ron too. after that harry goes bad really bad and kills draco or his mother narcissa. then he cant stop he goes all the way bad so bad that no one can stop him he goes on a rampage killing everyone muggles and wizards he ends up having some kind of truce with voldemort now that theyre on the same side until he turns on voldemort again and he gets worse than voldemort. but voldemort cant stop him alone so the only way to stop potter is for voldie to join forces with dumbledore. and then harry kills dumbledore and realizes what hes done then comes back to the good side finally finishing off voldemort. this way we can see how powerful harry really is because he will have beaten the two most powerful wizards alive at the same time. and i suspect dudley has something cool to do too. and yeah yeah maybe snape is a vampire and pettigrew kills him and lupin on harrys orders, because he owes harry for saving his life.
or maybe it finishes nice and happy and ron and hermione have a baby and they name him harry. but i think harry might die in the end because then why would the books end right when the great harry potter learns everything he needs and graduates from hogwarts, it should get even cooler now that he knows everything. but the books end with the last year of school and so does harry, maybe
There is definately something coming up with Harry and Malfoy and its going to be dark. Malfoy blames Potter for the incarceation of his father and I expect he may go to the lengths of attemping the murder of Harry of one of his friends. We have seen in the previous book that Harry too has his dark side largely as a result of Voldemorts power within him. I think in the next book Harry will have even more anger and bitterness due to the death of Sirius, I expect there will be a scene where Harry almost kills Malfoy at the spare of the moment, the good within him will prvent him from delivering the fatal blow.