Voldemort has won.

Harry and his friends have failed to rid the Death Eaters and their goals the previous year, which means only one thing: The Ministry has fallen, Death Eaters are now in control, and the Wizarding World is in some serious trouble. But that doesn't mean there is anything wrong of trying to do something right again.

Dumbledore's Army is off. The Order of the Phoenix is back, gaining and decreasing, and Lord Voldemort's most trustest Death Eaters work together as the Minister. Diagon Alley is frequently full of constant dark wizards, Knocturn Alley being even worse. Death Eaters swarm to Beauxbatons, Durmstrang, and plenty of other wizarding schools. Muggles are terrorized, Muggle-Borns hunted down, with halfbloods and purebloods given two diverse choices: Join Voldemort or be hunted.

...the students at Hogwarts are also given a choice, and each choice will be affecting their future.

Of course, Harry Potter, Ron Weasley, and Hermione Granger are important in this legacy, but this doesn't mean that the other students and staff of Hogwarts are meaningless. Depending on whatever the "Golden Trio" choose to interact with, they draw more people into their fight to save the wizarding world. Depending on whatever Voldemort does, more students and staff will be mentioned in prophecies and stars.

Depending on how well the students, staff, and other people do their jobs--fighting for the Order or the Death Eaters--the wizarding world would either flourish and get rid of Voldemort, or be under his control for the rest of enternity.

It's all up to them.