I understand, but that would leave a vacuum and you are sorely misguided if you think Russia won’t want fill it. They are already trying. It of course wants to be the new “policeman.”
(Which would be awful especially if you grasp what a Russian concept of “police” means even in its most basic sense.)
Or that China won’t fill the economic vacuum — which is why it’s great a trade war has started.
We should not fight pointless wars, but the world is a very dangerous place when USA takes a backseat. Someone is always willing to replace us out front. And its usually someone bad.
North Korea de-nuclearization talks? Fat chance in a world without Trump.
Both Russia and Chine a light-years away from having the global influence of the U.S. To talk as if their influence in Syria somehow remotely upsets U.S. Hegemony is quite hyperbolic.