As I understand it (I could definitely be wrong) China's concern isn't geopolitical but pragmatic: the immediate aftermath of the collapse of the DPRK would be a gigantic flood of refugees into China.
That is how I also understand their position currently, but I'm not sure that makes sense as their reasoning initially before the situation was so extreme (I'm assuming it wasn't, though I suppose war refugees of any sort can present an issue).
Why would it not result in a flood of refugees to S. Korea (ROK)? Unless you're saying that the indoctrination is such that they would rather flee to another (more moderately) centrally-controlled regime versus a free democracy - one that shares their culture (ignoring the most recent 60+ years) and language?
