Sorry to divert the thread back to its origins but I thought I would throw in my 2 cents.
At uni, one of lecturers was fairly adamant that there would unlikely that there would be another war on the Korean Peninsular because China would never allow North Korea to instigate it and the U.S know that China would punsih them if they or South Korea instigated it.
If there was an outbreak of war in North Korea, there would be a mass exodus of refugees over the border into China. As you can imagine, this is the last thing China would ever want. Similarly, given the catastrophic nature of a war in Korea or out of Korea (insane population density, destroying one of the best industrial powers in the world-South Korea and the potential for nuclear carnage), I imagine even the U.S would probably try and prevent it from occurring.
As far as winning the Vietnam War, whilst it is generally stated (in Australia anyway) that the North Vietnamese and their sympathisers won the Vietnam War, there were no real winners. The Vietnamese may have EVENTUALLY humiliated the Americans however at a cost of 2-3 million lives and the destruction of their entire country's infrastructure and culture. This hardly seems like a desirable outcome for the average Vietnamese citizen. Furthermore, the Vietnam War destabalised the entire region for the following twenty to thirty years.