What other option does China have but to wish its neighbour well. Good luck to another Kim reign?
China unlike US and NATO loathes at military intervention in other countries.
It is not in China's tradition and style to arm twist and force medicine down its friends' throat what it does not want to do. Behind the scenes, China has kept North Korea in line and averted potential conflicts when US/ NATO forced it to the brink.
Armed forces (military and police) are meant for defending its territorial integrity and maintaining domestic stability when forced by circumstances, just like the pre-world war USA until Truman came along and that was when exceptionalism by spreading democracy through military means began.
As the Chinese saying goes, wealth and power will not last beyond the third generation.
Perhaps the Chinese are hoping for a quiet evolution instead of volatile revolution next door.