An increasing number of South Korean analysts and journalists, who specialize in covering North Korea, believe that the collapse of the northern government is inevitable, and will happen sooner (within five years) rather than later. Few believe the current North Korean government will still be around by the end of the decade. The problem is, no one is sure what will replace it. It seems likely that whatever new government appears in the north, it will be controlled by China (which made it clear that they do not want a united Korea, as in South Korea absorbing North Korea.) South Koreans are inclined to go along with this. But as long as Korea is divided, reuniting it will always be a festering issue for Koreans.
As the moment of collapse in the north gets closer, more South Koreans are agreeing with China taking over up there. For the last two decades, South Korean reunification experts have been studying what happened in Germany (after the communist East Germany was absorbed by the democratic West Germany). That cost the West German taxpayers about a trillion dollars. Estimates of what it will cost South Koreans to absorb North Korea are now close to three trillion dollars.
Well, that would take care of the pile of money that China has accumulated the last couple decades, eh? I wouldn't want to blow my money on that, but what do I know?