The US is looking more and more like ancient Rome. In 10-15 years it likely neither can win a war against China but it will also likely not have many allies on its side if it tries.
China doesn’t have many allies either. They have managed to piss of just about everyone. There are few countries in Asia that wouldn’t be happy to see China taken down a peg or a dozen - and probably wouldn’t mind discreetly giving the US a hand.