There is no good north korea timeline. The entire revolution that created it was for the express purpose of putting an idiot dictator in charge, one who immediately went to work on forcing the population to consider him a god king and putting his equally selfish, stupid, paranoid, and vile progeny in charge.

Unless you believe a unified korea without US intervention but still with USSR support would suddenly overthrow that repressive regime, that was never going to produce a free society.