Maybe not so much under China’s sphere of influence, as just being more neutral without the US troop presence.
After all, how much is our presence in South Korea costing us today? If the threat from the North goes away, how do we justify that cost?
“After all, how much is our presence in South Korea costing us today?”
Cost in relation to not having a presence to counter NK and China? Probably it would cost more if US had no Korean presence and China starts taking over South Korea or Japan.