In 40 days (one round trip from US to China), the system clogs and the boats can't go running off because they can't unload at all (happening now). At this point the system stabilizes. Sure, it's not a stable point that the shipping companies want, but it is stable.
Capitalism has a way to deal with this. It's called "rising prices". However, business managers have gotten far too used to never suffering any consequences for their decisions. The moment actual responsibility comes down the pipe they all start whining and running home to Daddy (the government) for help.
Let the ships sit. When the shipping companies lose more money with a sitting ship that can't be unloaded than they gained racing back without empty containers, it will correct.