Among other things that are going on, there seems to be a lot of speculation in major U.S. publications, among the South Korean Press, and, well, pretty much all over the place about what to do about North Korea. Though domestic U.S. media is currently preoccupied with the BP spill ($30+ billion dollar loss in market cap), there seem to be almost a daily number of articles & incredible number of editorials on the topic in the past couple weeks... Well, here's my position South Korea should do nothing in full FDR fashion by switching from blaming U.S. and Japan for hampering Korean reunification to Chinese selfishness ("stability" so it can get "rich") and support for North Korea (the hapless North Koreans, who are being taken advantage of by the Chinese). I meant in full FDR fashion as a way of slowly building or manufacturing consent (whichever term you prefer) for possible unification. In material terms, South Korea should do nothing as NGOs don't seem to be particularly effective and, just let North Korea be -- without subsidies. Nothing else though.
Similarly, I believe North Korea's opportunity to receive U.S. aid (or the U.S. just buying out North Korea's WMD program) has come and gone. So, I'd suggest that it is high time to prepare the South Korean public for unification -- FDR style. I mean there is the planning over the what ifs -- I spoke earlier about OPLAN-5029, which details U.S. and South Korean (ROK) armed forces crossing over into North Korea primarily to secure North Korea's weapons of mass destruction (they have stockpiles of chemical and biological weapons that get less media attention, though I'm not as sure of the latter). But, this is just one small aspect. On a side note, unlike Iraq or Afghanistan there is also a rich country with the right people to occupy the country, if necessary. Though, of course, unlike invading Iraq or Afghanistan, the war might turn out to be much more like World War I, but against a much more suicidal enemy (kind of like Imperial Japan).
With the current Cheonan sinking incident it's time for the South Korean government to slowly manufacture consent not unlike the Sunshine Policy, which did the same against unification for the past deacde. For example, anti-North Korean sentiment should naturally be diverted to anti-Chinese sentiment since South Korea really can't (and shouldn't) do anything (For example, long term DPRK concessions to the Chinese, such as, the port of Rajin -- which looks like a reality, should be as well known as Dokdo).
The U.S. should continue to give symbolic assurances (aside from ratifying KORUS, which goes beyond the symbolic and which should have been ratified much, much earlier) of U.S. support for South Korea and. For starters, avoid (skip) the six-party talks until the Cheonan incident get's resolved and Kim Jong Il dies. This should serve to build pro-U.S. support for any unified Korea or for whichever type of regime comes next. Given South Korea's national psyche and inclination to blame outside forces, this shouldn't take too long. If this is indeed what happens, we'll be less likely to hear from Korean press about Dokdo (Liancourt Rocks) and more about Goguryeo (Goguryeo) for a long while.
I don't put much weight on the thought of the Chinese ever deciding to actually add North Korea to China proper (I mean North Korea is not a Xinjiang or Tibet. And, I think there's probably a reason why nobody aside from the Tang Dynasty in the 7th century and Japan in modern times really tried to annex Korea (though I believe it was discussed in China during the latter days of the 19th century to ward off Japanese influence and it's not just because of the historical, tributary system in Asia). Imagine trying to govern the most xenophobic, nationalistic, and ethnocentric (perhaps, racist) people in the world.
Moreover, I'm not fully convinced that China is fully backing the North Korea regime. If anything, China would love to be in the position of the United States -- hence, the reason why the South Korean President was met days before Kim Jong Il. Moreover, these concessions in the form of long term leases of ports (Rajin) or mines, etc, seem more like short term hedges against a North Korean collapse and just create North Korean resentment toward China. And, if anything, while we always consider how South Koreans might lean in the event of unification, I'd bet that current Chinese policies in North Korea would cement Anti-Chinese sentiment among North Koreans in a future, unified Korean peninsula for generations.
After a couple of decades as being the lone ranger in Northeast Asia (Japan and Australia really don't count here), it seems the U.S. is finally in a rather nice position.
China? Decidedly, less so.