When my home airport was LAX, I flew almost 1MM on AA, then I moved to ATL. I continued to fly AA until I went over the threshold (1,006,323), then switched to DL. That was 11 years ago. Still "permanent" AA Gold, but have only flown a couple of times on AA since. No call, no email from them, just announcements about every 2 weeks to say, "you're almost eligible for an award ticket!".