What Xi's reaction is and how Trump takes it could determine the outcome. My expectation is that Xi will agree to do more than what China has done so far. Relatively speaking, it could be significantly more than what they used to do. But it may be still short of making any lasting impact: something which can cause a lot of pain for N. Korea for several months and up to a year, but not enough to change N. Korean behavior regarding nuclear weapons and ICBM's. It may be able to make N. Korea postpone some test, but I am not even sure of it. In return, Xi will ask significant concession on trade front.
In the end, what China would do is to keep things quiet and stable for about a year and after that, things will go back to where we are now. By that time, Trump is besieged by other problems, and the momentum for any action toward N. Korea peters out, China may hope.
Even if China succeeds in this gambit, such an inaction from U.S.'s part will compel Japan to act aggressively. If China dodges Trump's bullet, they may end up facing Japan's nuke.
Another possibility is that Trump declares that the red-line has been crossed, and China only gets to haggle over the price for acquiescing Trump's action.
If Xi balks or plays delay game, would Trump walk out or fold? That seems to be the question.
I agree, but the Chinese population has get used to increased wealth are getting problem due to the problems in the banks (although there are signs of some improvements
https://www.bloomberg.com/news/articles/2017-03-30/biggest-chinese-banks-bad-loan-challenge-may-finally-be-easing ) and this increases the probability for domestic problems. Often such problems are shifted to a blame game and for China it means the foreigners.
Even if Xi is prepared to make a deal with the West he has problems with his nationalistic “electorate”, but I guess that his “electorate” is not fond of “Kim Fatty the Third”.