The problem is that as we're seeing with the Strait of Hormuz, "the USA forfeits its global ambitions" does not lead to a new age of peace and sunshine, but to global recession and instability. The Strait of Hormuz is not the only load-bearing instance of US power backstopping modern economies.
I think the traditional answer is actually "forfeit your global ambitions because you can't afford them and voters won't make the sacrifices necessary to restore them," unfortunately