Dumbledore is alive but in hidding.

Severus Snape is dead. Severus has one daughter and one son. Amungst things, Severus's daughter and son are seeking to avenge there father's death by going after Potter himself.

Seruas, and Malici blame Potter for there father's death. They see probable cause that Potter was the traitor of there father. Malici has some clue that his sister is also trying to gain revenge on Dumbledore.

Lucius is now widowed and his son had also died in the war. Lucius Malfoy is now the new Dark Lord. He is seeking vengence on Severus by trying to cause mayhame against his daughter. Seeing that Severus's son is not so much an easy target as his daughter is.

Potter is now the leader of The Order. Mcgonnagal is co-leader of The Order and Headmistress of Hogwarts. With Lucius not so much as a huge threat as Voldemort himself was; The order can now recurit easier and plan. Blinded by there new threat.