The US has a history of walking away from a defeated or...

The US has a history of walking away from a defeated or stalemate position in wars since and including Vietnam. Saving face is not really a big part of the American culture, but for China it is an imperative not to show any weakness. Life is fairly cheap there, witness the mass starvation under Chairman Mao Tse Tung. The state comes in first, the individual last. Trump will eventually get a small concession from China and say he has been successful then likely drop the whole thing. Above all, he wants his second term.