Steven has a detailed and thorough post about a radical solution to the NK problem - letting China win. It's a subtle argument and is not well served by excerpting, so I won't try. But it certainly is the kind of foreign policy that would be more achievable under Reagan, Bush Sr. or Clinton (in that order). Under the neocon domino warriors/reluctant imperialists camps that currently compete for the reins of the current Bush's foreign policy, the idea is ultimately impossible, because realpolitik requires the Administration to willingly suffer a loss in prestige for the greater good. Allowing China to take over NK would amount to a loss of face for Bush - and as we know, neocons are a very face-oriented culture.
China is indeed rising though. By all measures - economic, military, population - China is building a foundation for primacy. As long as China remains Communist, though, her gains are a zero-sum with our interests.