North Korea is so far back economically nobody would be willing to spend all the money to shorten the gap between them and even South Korea in case the communist regimes goes down. It just doesn't make sense. Look at Germany, 30 years after the fall of DDR, East German lands are still believed to be the "poor" ones compared to the rich GDR in the West. And that's with all the EU support and all that. I read an article few years ago where it states the world doesn't really want North Korea to become democratic because it would take an absurd ammount to make to help them so it's better the communists stick around while under sustained pressure from China. This also belefits China, they can manipulate the Western world by supressing Kim's ambitions while being granted the international free market leeways.