Once the vanguard seizes power and becomes the dictatorship of the proletariat they will naturally act to preserve their own power, preventing the withering away of the state necessary for higher-stage communism. The duty of anarchists, since their end goal is the same higher-stage communism, is therefore to form a new vanguard with goal of ending the dictatorship of the proletariat.
In practice, however, this is never observed.
@ghost_bird One does not establish a dictatorship in order to safeguard a revolution; one makes the revolution in order to establish the dictatorship.
George Orwell, 1984
A fire is burning in Bird Spirit Land.