This time Xi is strong-arming Kim into doing things the Chinese way. I think Kim Jong-un still counts on S. Korean gov to revive economic investment in N. Korea. However, since U.S. leans hard on SK, it is not a sure thing. Even more so, if Kim is going to rebuff U.S. proposal and push for drastically scaled-down denuclearization.
I think Kim still hopes that SK can deliver enough goods to him so that he does not have to entirely rely on China.
I think Plan A was that N. Korea become an independent free agent neither tied to China nor to U.S., with his nuclear arsenal ready. Play off one against the other, and get money from everybody. In the meantime, steadily advancing his project of defacto takeover of S. Korea. A kind of grand dream but China stomped on it hard.
Sooner or later it will be big changes in NK, and then the money and trade flows will be in charge, not the Juche priests. This https://en.wikipedia.org/wiki/Gravity_model_of_trade will be a big factor.
A rough calculation: To increase the standard of NK to a suitable level about $100 000 is needed per capita for the next decade = about 25 M x $100k = $2,500 billion. With > 15 % profit margin that is more than $250 bn in profit. This is a conservative figure.
If I were to give advice to the Norks I would say; “Make sure that you have good relations with Tokyo and Washington otherwise you will be swallowed by Seoul and Beijing. Perhaps you as well need US forces and bases for protection.”