Why not? Certainly there are a large number of historical counter examples to that statement. The old guard dying off leaving more progressive elements in the l

Why not? Certainly there are a large number of historical counter examples to that statement. The old guard dying off leaving more progressive elements in the leadership to bring on reforms in a country. The death of Mao in China and the trial of the Gang of Four marking the end of the Cultural Revolution. The death of Franco in Spain and the transition to a constitutional monarchy.