Nothing much. North Korea, at some point in history will open up and join the league of nations that trade with each other...maybe slowly like Cuba is doing. Until then, I doubt they even have enough bullets for their soldiers to fight a conflict. Just like all recent strongmen, it's much more bark than bite.
The reason why "only" 1 million N.Koreans died of hunger during their famine, was because of China. Without political cover by China, N. Korea would have been long gone.