I wouldn’t try to make a prediction about the likely future course of North Korean affairs, but clearly the state could collapse rather suddenly which raises the question of what would happen next. Minxin Pei says the world is unprepared:
What is most worrying about a possible North Korean collapse is that the key players in the region are not talking to each other, even informally, about such an eventuality. It’s almost certain that these powers — China, the United States, Japan, South Korea and, possibly, Russia — have all drawn up their own contingency plans for Pyongyang’s quick collapse. However, they’ve done nothing to explore a collective response to what is without doubt a geopolitical game-changer.
It seems to me that if there were such talks they would be secret and not just “informal” so it’s hard to know if this is right. But I agree with Robert Farley that in many ways the harder case is if the DPRK doesn’t collapse, but instead finds itself with a post-Kim leadership that just comes to the world hat in hand looking for help:
Collapse is certainly a possible outcome, but it’s also possible that the North Korean state could survive, at least for a while, under some sort of non-Kim military dictatorship. The attitudes of Seoul and Beijing would be particularly important in this respect; the health of a post-Kim North Korea would be greatly affected by China’s willingness to underwrite the regime, and by South Korea’s approach to manifesting claims on Korean national identity. In the German case, the Russians had no interest in continuing to prop up the Berlin regime, and West Germany was happy to advance the claim that it was the only legitimate German national regime. It’s also worth noting that nationalist sentiments could override such a pedestrian concern as the utter economic disaster that incorporating North Korea would wreak upon South Korea.
South Korean elites are certainly aware of how difficult German reunification proved to be and how much more difficult Korean unification would be. But I have no idea whether this is understood by a mass public in Korea or if there would be a strong initial drive to push for unification irrespective of the practical problems.