You eloquently elaborated the decline of the western power in the 21st century and the loss of faith by the world at large in the empty promises and democracy vowed by the US to bring about in Afghanistan. I appreciate your view that China should not join the war of  western forces in Afghanistan, since it is not China's business to plant a so called "democracy" there in lieu of Taliban. After all, it is up to the Afghanistan people to choose and decide.

I also find it difficult to concur with your scenario of a possible US invasion of China via Wakhan Corridor in case of a crisis or war  over Taiwan independence. Given the fact that US troops is confronting with enormous difficulty to win the fight against Tabliban guerrilas, it is not too hard to envisage what will happen if the US troops would invade via Wakhan Corridor into a vast country with the largest standing Army of the world which the forefathers of the US Army after the Korean war had warned: never engage Chinese Army in a ground war.