What a lot of armchair experts here who are stuck in the Cold War.
First, no, China is not the Soviet Union. When one dominant ethnic group is 93% of the population (and much of the remaining 7% are mixed Han/minority who declare themselves as minority in order to qualify for affirmative action schemes), there will be no Yugoslav-style collapse.
Second, I can foresee a crisis which causes Tibet and Xinjiang to split up (but not Inner Mongolia, which is 80% Han), but they will quickly become totally dependent on their vast new neighbour. Tibetan schoolchildren and businessmen will still be required to learn Mandarin to succeed. Almost all the trade will be conducted with their new neighbour. Perhaps they will depend on it for military protection. By this point any sense of independence becomes blurred.
Third, I'm not aware of any country descending into civil war after its economy has grown above a certain point.
Fourth, any notion that Chinese culture is incompatible with democracy and liberalism is nonsense. Korea and Japan prove that Confucian values can coexist with liberalism (the former proves how one culture can form two totally opposite regimes). Taiwan *is* Chinese, and has been democratic for 20 years without much trouble. Hong Kong (under the flag of the PRC, no less) *is* Chinese and *does* have democratic and western values, and has been that way for decades without any trouble. No doubt the latter two will do much more to promote those values in the PRC than anything else will.
Fifth, if anything Korea and Japan are more xenophobic and nationalistic, since their small size enables a culture which is uniform across the entire country with little foreign influence. Many provinces in China are more culturally diverse than those two liberal, democratic countries. So any cultural explanations for the dictatorship is nonsense.
Finally, it is possible for the Communist Party to relinquish power. Supposedly "free" China, a.k.a. the Republic of China in Taiwan, was ruled by an authoritarian dictatorship until the late 1980s when controls were gradually loosened. In 1990 students demonstrated in Taipei demanding democracy, which the government had no choice but to accept.
People need to accept that this isn't the 1980s and there is no evil empire to bluster about