I can remember a 1987(?) Aviation Week article discussing FedEx's new A300's. It said it was FedEx's intention to retire 2 727's for every A300 received? I guess that didn't happen?
More recently I read that the 757 was going to be the 727 replacement? According to Capt. "O", it now seems to be an A310 replacement instead?
Maybe some future A380 order will end up being the 727 replacement?