A note. You can't declare the Korean War to be over unless. . .

you acknowledge it was a war in the first place.

Sounds silly, I know.  But wars only occur between sovereign states.

If the Korean Conflict, its official name, can be declared "over", it has to have been declared to begin, and that would require acknowledging that it was a war between two sovereign states.

Which has never been the case for North or South Korea.

Because if that's acknowledged, then the concept that there's one Korea is effectively over.  There would be two sovereign entities, each with a right to exist, in perpetuity. 

Sure, two sovereigns can unite.  But a unification would note be the official presumption. 

And changing that is a major change, should it occur.