RSSI agree. I am also reminded of the Highway of Death in the Gulf War in which Saddam’s conventional armored assets were destroyed by superior US air power. I see the same scenario in Korea since the US and ROK will quickly establish air superiority and obliterate the NK invading forces. The 10s of thousands of NK regulars and conscripts trapped behind the DMZ will either face annihilation from US and ROK airpower or surrender.
But for the need to contain North Korea, the US has no reason to station military assets on the Korean pennisula within easy range of Chinese missile defenses. Reunification would allow the US to maintain a strong presence in the North Pacific from existing an better equipped naval and air bases in Japan and Guam. Ultimately, a Korea reunified by the South is best for both the US and the PRC in that it would exist as a mostly demilitarized buffer state.