Here's the thing. China has a 3 part political system today - Party, State, Military. In the past, especially during the Deng years, it was that the Party led the State and Military. In particular, the military is considered not just a national military, but a PARTY military. It was not always like this of course. In Mao's day, the PLA was considered a national military alone from 1949-1954.
If the Party, State and Military are united, there's no problem. However, what we see today is the Party, State and Military going on different directions due to differing collective interests. It is in the interest of the Party for China to reconcile with the US; however, it may not in the interests of China (the state) and the military to do so. This is just 1 example. More important differences lie in their fundamental views on national interest and political development. General Liang Guanglie, Defense Minister of China, has called for the independence of the military from Party control, which he believes will strengthen the military. Premier Wen Jiabao has called for political reform and increased democracy. Both of these are DIRECT threats to the CPC, and the CPC (or more precisely, the clique that has hijacked the CPC) will not accept it.
If they make changes too slowly though, or refuse to budge, then there are things that the state and military can do. The state controls the police and the military, well, is the military. The CPC on the other hand, alone, has no physical power; the entire CMC is made up of generals, excluding Hu Jintao and Xi Jinping. If political reform is too slow, or the interests of the military is threatened by the CPC, then it is very possible for a military coup to occur which would remove the civilians of the CPC from power, in the style of Gorbachev and Yeltsin.
Then, hopefully, the PRC survives as an entity, suffers 1-2 years of low economic growth, and gets back on its feet. In the worst case scenario we break up like the Soviet Union and become enslaved by the West.