South Korea today is quite capable of taking care of itself in ways which were not the case a half-century ago.
I don't want to see Americans pull out of the Korean peninsula. But if that ever were to happen, I doubt it would help the North Korean government. It might, however, help China if South Korea came to some sort of agreement with the Chinese on how to get rid of the North Korean annoyance.
I served a year in ROK while in the US Army.
I wouldn’t be too sure about ROK surviving if the USA leaves.
Reunification is very popular...and there are plenty of socialists.