I’ll bet those troops are not there to go into NK .... but focused on SK and US troops in SK.
Have you looked at Chinese media reaction to the Xi visit? Extremely positive. This is not bad in any sense of the word, bad. It is a mind blowing change in US/China relations. It is an overt threat to fat boy. Wait till we deal with Iran. China will be involved. Splitsies are fair aren’t they.
I doubt it. Neither China or Russia are sure the numbskull in NK won't launch a nuke at them since he doesn't come to heel even after they help him.
As long as China has a say in who runs NK instead of being reunited with SK without any Chinese say in how it is organized and run they'd probably be glad to see the leadership change. They have plenty of problems with NK other than nukes, too.