Sirius is dead, so is Dumbledore. They're going to stay that way, no question about it. Ron and Hermoine will get together, then one will die, Snape will hurl himself in front of an Avada Kedavra curse aimed at Harry from Voldemort, Hermoine will use her coin to call the D.A. to help them fight Death Eaters, and the D.A. will bring other students along with them so that the students fight the Death Eaters while Harry fights Lord Voldemort. During the battle, Malfoy will join the students against the Death Eaters and kill or capture his father in a duel. Harry will kill Voldemort, any Death Eaters not dead will be captured, and the story ends with Harry becoming the DADA teacher at Hogwarts.