FWIW, I’m flying TYS-ATL today ~30 min flight time. I was offered a $450 FCM at check in. And I’m 4/28 for one seat. I was watching the flight for a few days and there were maybe 3 seats open a week ago.

Which tells me that there are plenty of people paying for F. Maybe these folks are going to Europe out of ATL. Maybe there are a bunch of rich people/folks flying on OPM flying domestic F.

There are also at least 4 DM on my flight (me plus everyone above me).

As DLATL777 notes above, the upgrades at all the airlines have dropped off over the past 10-20+ years. I used to be upgraded regularly on US between PIT and SEA as a silver equivalent back in the 1990s. But between then and now, how may airlines have been forced into merger or bankruptcy? And in the same interval, F seats have gone from being ~3x+ coach to frequently only 25-50% more.