I also believe that if China did not have a powerful central government it would break into several republics, starting with Xinjiang and Tibet.
But the interesting part of this is that the central authority not only works to stop secession movements, but also to make sure minorities have a place in modern China. In general they try to favor minorities getting into college, by lowering the grades (from the overkill high school test) a minority student needs to enter college. That and general promotion of a minority's culture in primary school (like dances, language, etc) tend to ease the friction that both the Han have towards some minorities and the minorities have towards the Han Chinese.
But the interesting part of this is that the central authority not only works to stop secession movements, but also to make sure minorities have a place in modern China. In general they try to favor minorities getting into college, by lowering the grades (from the overkill high school test) a minority student needs to enter college. That and general promotion of a minority's culture in primary school (like dances, language, etc) tend to ease the friction that both the Han have towards some minorities and the minorities have towards the Han Chinese.