Thanks for sharing your input, so in other words, you believe that the Korean interstate paradigm is being used as a proxy mechanism between Washington and Beijing and is in fact a tool for both powers to have control / influence in the region. I don't necessarily disagree with this analysis.
Like I said, China's policy on N Korea is very simple. No war, No collapse and No Nuclear Weapons. In that order.
It boils down to stability to allow China to develop and catch up with the West.
You can do anything else. You can talk. You can sign a peace theaty. You can trade. Korea can even reunite peacefully.
The problem is United States. US will never deal or sign anything with a person like Kim Jong Un. Period. They only interested in regime change through force. Nothing less.
They are happy to just keep intimidating N Korea. Even happier if Kim set off more rockets or bombs. It allows them to justify increasing military presence in S Korea.
As for Japan, the last thing Japan wants is a united Korea. That's nothing new.
So....If North and South Korea gets too friendly, both United States and Japan will do all it can to sabotage it. And that's pretty easy to do with a thin skin Kim. Like once when Dick Cheney called him an asehole. Or make a claim about Kim Jong Il printing fake dollars. Or in the case of Japan, bring up the kidnapping cases. Or hold more military excersices.
The problem has nothing to do with China. China just want peace in its backyard.