I've been an AA PLT on BA several times throughout the years and have never had (nor expected) an upgrade.
Last year I did MAN-LHR-SIN-SYD-SIN-LHR-MAN (22,344 Mi) all in coach on BA in 6 days. On the day I returned, they were throwing a party at LHR for some blogger who had flown 15k miles in a week... During my return layover. I rolled my eyes and kept walking.