Book 7 facts.
These are things that JK Rowling has actually said rather than speculations:
Harry will be 17 years old. He will be in his last year at Hogwarts and will come of age in the Wizarding World.
During an online chat at Scholastic, JK Rowling was asked: "What makes some witches/ wizards become ghosts after they die and some not?" She replied: "You don't really find that out until Book 7, but I can say that the happiest people do not become ghosts. As you might guess Moaning Myrtle!"
JK Rowling has said the last word of the last book will be "scar!" Now she says that it may change during the writing of Book 7.
Will Snape be redeemed in Book 7? Perhaps a romance? JK Rowling has alluded to the possibility! We shall see...