What you need to worry about is what the ex-middle class people will do when they're poor, when they have nothing to lose. Look in history books at what brings on a revolution --an overthrow of power. Look at the French Revolution --- they haven't had one since they've had a middle class. Angry peasants aren't good to have around.
Restrictions against self determination; including the ability to personally improve one's living conditions, combined with the loss of basic human rights, is what is responsible for revolutions.