I might agree with you about China given the vast amount of corruption. I doubt they'll kill their golden goose (trade with the West). If the Chinese economy collapses, it's hard to predict what they may do to retain power and distract the populace. Iran and North Korea are cut from different cloth. Iran is a state sponsor of Islamic fundamentalism. North Korea exists for the benefit of one nutcase and his family. Neither will allow capitalism to flourish unimpeded.
North Korea's dependence on selling missiles and who knows what else, nuclear warheads perhaps, for hard cash will eventually create a problem the world will regret. It's not impossible for a New York City or Washington D.C. to be hit. Those are prime targets.
I'm waiting for the bunker buster sale to Iasrael to be consumated. With luck we can add Iran and North Korea to the list which includes Iraq and Libya as nations no longer interested in nuclear weapons. I'm betting that will happen before 2008.
"Iran is a state sponsor of Islamic fundamentalism."
However, that nation is already liberalizing..its a great chance to try the free-market capitalism alternative.
"North Korea exists for the benefit of one nutcase and his family."
You may be correct about North Korea...but I feel diplomacy and trade should be the first alternative. Let us see how ambitious Jong-Il is....and if that doesn't work...he certainly wouldnt want to nuke the place where most of his favorite pop culture comes from!