No one thinks China is stupid, but historically they have had at least four valid reasons to support North Korea: Fellow Communists, physical buffer against South Korea and the West, keeping an economic competitor permanently weakened, and potential loss of face in having a Chinese client state fail or be taken. If significant factions of Chinese leadership have turned against North Korea, and assuming those are primarily the younger generation, then only the fourth holds true. Thus as long as South Korea and the West do not act in such a manner that threatens Chinese leadership with loss of face, reunification is not only possible, but somewhat likely.
LOL I imagine you are correct with this analysis.
Those four things you list that don't really matter at all. First off China is hardly communist and one could make arguments against N.Korea being communist as well. N.Korea is a "spoiled child" and a parasite to the region, they actually cause harm to China by just existing. The buffer from Korea and the West isn't needed any longer. South Korea and the USA are big trade allies together and with China. The USA and China are so tied together that the failure of one is the failure of both. Loss of face is big for the Chinese people, but I think they would rather prosper and lose a little face than destroy everything they have been working so hard for.
Like I said, you have to assume China is stupid and would not act in its best interest for these doomsday scenarios to occur.
