Possibly. The question is what will North Korea do if China comes over the border. Their traditional enemy is Japan, South Korea and America. Will they pull an Iraq and attack the county that isn’t involved?
If China did “come over the border”, would they use tactical nukes?
Very likely they would, if their military leadership is completely under control and as fanatical as is usually assumed.
The rational assumption for those people is that NK is not a viable state without a friendly China, and with a hostile China it means the NK regime will be gone in short order. The question is - just how irrational are they?