Overall, an excellent example of a well-reasoned, thoughtful (and even concise) summary of the issue. Huge changes probably not going to happen for a while.
As to LAX, a couple of details might affect the balance.
1. Don't forget AA's preferential use of four new gates at the rebuilt TBIT and the T-4 to TBIT connector that was approved two weeks ago (at a frugal $107 million total appropriation by LAWA); and
2. Depending on how many gates US obtains at T-3 when it moves from T-1, there may be a possibility of slight expansion in the number of domestic flights. I don't know how crowded T-3 is with VX and B6.
Sure, the T-4 to TBIT connector is a three-year project (that may take 4 or 5 years total) and T-3 to TBIT/T-4 requires a bus or outside stroll and additional TSA X-ray, but T-3 gates could be used for the flights that are more heavily weighted to local O&D and feature fewer connecting passengers. Flights that are more connection-heavy could use T-4 and/or TBIT.
One last thing: Several years ago, AA pushed more mainline flights thru T-4 than it does now, so there is certainly some additional unused capacity. There's interwebs rumours that JFK-LAX frequencies will increase with the new A321s (to make up for the greatly reduced seating capacity), so if true, that would absorb some of the slack. On the flip side, AA should be able to turn a 102-seat A321 a little faster than a 168-seat 762. Some of the interwebs rumours say that there will be two dedicated T-4 gates for JFK flights.
My back of the envelope calculations result in an estimate of about 200 daily mainline flights as the potential max for new AA at LAX (based on three T-3 gates, the four new TBIT gates and the historical capacity of the 13 T-4 gates). That's based on a flight activity day that runs from 0500 to about 0200.