APM is schedule to open in 2023 so the current arrangement will last about 3.5 years if construction stays on time (should be... there is no land acquisition left so no more lawsuits to significantly delay this project).

As for traffic mitigation due to more terminals... I don't think it will have any big difference in passenger levels for the next 3.5 years. MSC North is opening in 2020 but mostly just reshuffling existing service so LAWA can give AA more T5 and TBIT gates. Not a whole lot of new service will be added.

Concourse 0 probably can't start construction until the current ride share lot moves to ITC West or ITC East with APM opening. So we don't have to worry about that adding new passengers to the mix before 2023.

MSC South and T9 are both planned after 2023 as well so by that time, the traffic pattern will be completely different.