In my opinion the US would win a war without a doubt considering that our navy is simply too powerful and Russia and China would never be able to have broken a naval blockade.
In a Realistic scenario where there is no surrender, Allies, treaty or peace Russia and china would outlive the U.S.A (Mostly because they have better crowd control + Higher economy) but in the case that there is Allies helping each side U.S.A Has much more western europe support which would massively boost both their land control Russia and china have less allies that are less useful some in eastern europe and a few southern american countries in that case U.S.A (NATO) Would win. Then again i highely doubt this’ll ever happen