Easy for us to say, but I'll call it a bluff.
A war will be a set back to china's economic development and they need to achieve certain economic targets before they fall over the aging population cliff.
It's an open secret and even dotard knows this hence his willingness to push China to the brink on Korea and Taiwan. China being excluded from direct talks between Kim and Trump is very telling.
China's military hasn't fought a war since vietnam. They and their equipment are untested vs battle hardened US. Would their millennial little emperorers of the one child policy be an effective fighting force? It will be a blessing if we never get to find out the answer to that question.
China will want to avoid war as far as possible. Dotard will keep pushing them. Duterte is sucking up to China coz they don't give a shit about his human rights record. The people voted for him, so his position is legitimate.
And that is a sign of things to come if China becomes the leader of the Free world. Dictators will rise, citizens will suffer. All in the name of the mighty renminbi.