Even in the best case, reunification would be a long, complex and expensive process. The cost to the ROK would be huge. The influx of voters from an impoverished socialist land could transform South Korean politics. The South likely would turn inward to focus on knitting together two very different lands.
Moreover, the assumption that Korean reunification is the inevitable outcome ignores China. The People’s Republic of China is simply assumed to be a passive actor, a very large potted plant sitting just north of the Yalu River. However, Beijing would prefer not to see reunification, which could create a stronger, independent, nationalistic state on its border—one which could spur irredentist claims to Chinese territory populated by ethnic Koreans and would still be allied with the United States. Indeed, the possibility of expanded base opportunities, useful for containing the PRC, would complete China’s nightmare. Observed George Mason University graduate student John Dale Grover, “A world without North Korea would be dangerous for Beijing.”
That means the PRC might intervene to forestall such a result.