>>1903975specifically for these fleets: DC-10 and MD-11 has a huge useful load and long legs despite it's really short wingspan. They can park in B767 and A300 parking spots, which means parking on the wings of the sort facility in MEM/SDF, as opposed to remote parking on the field like the B747 and B777 have to. Parking on the sort wing saves alot of time, which over the course of a nite, less a decade adds up to alot of saved time (therefore money) over the span of the whole fleet. The MD-11 is being retired mostly because they're tired airplanes and the relative hangar queens of the FDX/UPS fleets. Combine that with the higher fuel burn it has and the Pratt birds hitting a hard maintenance limit soon, it's obvious that in this freight downturn, they're the ones to kill off.
There is no direct replacement for the MD-11, as the A330F neo is somewhat comparable in load, but (almost) has the wingspan of a B744, meaning it either needs to be parked remotely, or new dedicated Group 5/6 parking on the facilities. Also note that, the B767 & B777 Classic will no longer be authorized for production due to the queers in Europe making emissions laws, ending B767, 772 and 773 production by law in 2027. The A300/A310 have been out of production, and this leaves a GIANT hole in the cargo world. I forsee the A321F, A330F, B738F to become more popular used conversions, and a factory freighter A350 and B787 (probably the -8 model) to come online as factory freighter options. Note, the B777 has JUST had it's first passenger to freight conversion, that's how backed up the OEM factories are for new planes despite the demand for freighters NOW. There's now a market to STC it, and despite the B772 being the factory freighter, you need a B773 for a conversion due to useful load considerations. It's a bleak future when the only production freighter in the market is the B763/B772 which ends by law in 4.5 years.