Chinese pressure on the NORKs

I hear TV newsies talking about this.  The question is what can we do about the NORK nuclear weapons program.  The answer from a number of newsies is to get the Chinese to apply pressure on the Kim regime to back off on the nuclear program.  Sounds good. 
  But it won't work.  The Chinese don't dare apply any serious pressure, such as cutting off their economic support.  North Korea is in such tough shape that only shipments of fuel and food from China keep it running.  The Chinese fear that cutting the shipments would destabilize the Kim regime, leading to a total collapse.  North Korean agriculture is so screwed up that it cannot feed their people, and their industry is so feeble that they have invited the South Korean to set up maquiladoras in the north to employ some of their people.  The only things keeping the Kim regime in power are the secret police and the army.  Should either of these fail in a clutch,  North Korea comes undone.
   The Chinese don't want this.  They would loose their buffer state between China and bustling prosperous and pro American South Korea.  They fear that the South Koreans would subvert Chinese citizens away from communism and the one true way of Mao Tsetung.  Plus giving the Americans listening posts and air bases right on their border rather than way off down south on the 38th parallel.
   I cannot see China risking the loss of the Kim regime just to make the Americans happy.