Although China's been taking over the SCS, I haven't seen many open hostilities between South Korea and China covered in western news media, almost like SK ignores China's activities for the most part. I don't think there's any chance of a reunified Korea under the Kim dynasty or within 10 years.

edit: forgot to shoutout above's username

Considering a significant bunch of Korean companies have production facilities in China, I'd say the relationship is more amiable than say the Japan-China one. Both were aligned in protesting the release of Fukushima water into the ocean for example.