So unless the DPRK does something so incredibly stupid that it alienates China it will be safe.
And in that case, China would rather do the job itself, instead of allowing the Americans to do it.

I think the proper analogy is Georgia. As much as the US would like to bring those countries to their own orbit, there is a limit placed by the existence of other powers like China or Russia. Those may not be able to compete in a global scale, but within their area of influence they cannot be discounted at will.

Luís Henrique