I honestly believe China has sat up and noticed a few things. I don't think the Cruse missles or the MOAB was as much for N. Korean to take notice as it was for China to take notice. I think they have and have people in N. Korea right now telling Kim he should back off. Probably explaining that Trump is a crazier man then him. Of course, Kim may want to prove China wrong and do something stupid.
Kim knows better then to be the first with a nuclear weapon so he would start with conventional which would rain down on S. Korea and possibly some towards Japan. Kim would then know he was going to lose the war big time and in a show of desperation, probably try to launch any nuclear weapons that he may have left. Any way you look at it, N. Korea would lose the war and China is fully aware of that and fear what their price would be at it's end.