Apparently the Tiananmen Square protests of '89 (as well as the general political climate) caused such political turmoil that factions within the Chinese Communist Party, which controls the People's Liberation Army directly, began to turn against each other. Even today, there are cliques in the CCP that scheme against one another.
What would China be like today if there was a second civil war in the 20th century? How would this war go? Is the scenario even plausible?