It's amazing how little it takes to create divisions and how long it takes to reunite. I assume that the Koreas are looking at Germany's reunification long and hard, and I imagine they are scared shitless.
Korean reunification is almost incomprehensible. Germany had and has massive problems, despite the fact that East Germany did exceptionally well relative to the Communist world. North Korea, by contrast, is a total shithole even by Communist standards. Best case, it seems to me like North Korea would need to go through decades of reform and catching up before reunification could even be considered. And that of course assumes that the North Korean leadership comes down with a sudden case of acute sanity, which doesn't look likely to happen anytime soon.