Update--22 Hours From Flight Time
I just checked in on-line for this flight.
I'm #1 on the upgrade list, out of 2. There are still 10 seats open in F, 23 in Y, according to the on-line "upgrade list". This means they've sold one F seat in the last five days.
This begs the question--why did Delta suddenly take away all upgrade availability on this flight just before the 5 day window opened? What good is their promise to upgrade a PM 5 days out, particularly on a flight wide open in F?