Unfortunately, the MD11 and MD90 aircraft, which were the last designs issued by MD, illustrated a once-successful philosophy which was failing them. MD had had a group of very loyal customers who purchased almost everything that they issued. These included American, SAS, Swissair, KLM, Iberia, Alitalia and many others. On the basis of that, plus the success of the DC-10, they went ahead with the derivative which became the MD11. It is also significant to note that MD was ahead of the field in offering the MD11 as neither Boeing nor Airbus had a 300-350 seat airliner available and, by deriving it fom the DC-10, MD felt that it could keep its lead on the pack.
So said, so done. What they did not bargain for was American's 1990 disappointment over the MD11's performance which threw a spanner at their optimism. Meanwhile, Boeing and Airbus started taking orders for their all-new craft, 777 and A330/340, respectively. These planes represented all-new philosophies towrds aircraft design which made MD11 seem dated indeed.
Airbus on the one hand went for a wing and fuselage which could be adapted to 2 types - namely a twin for medium range flights (A330) and an ultra-long ranger quadjet (A340). By doing so airlines could purchase both variants and thus effectively upgrade their entire extended range fleets with one type of plane. Boeing meanwhile went for enormously powerful engines which propelled the 777 to great ranges with huge payloads. By careful design of wings and engine selection, Boeing has also been able to stretch the 777 considerably to the -300. Both Airbus and Boeing went for fly-by-wire, which MD never offered.
As such, MD11 represented a last-ditch fling of a dying concept, namely that of the trijet. With engines being so advanced nowadays, 2 could easily do what 3 were needed for before with much less fuel consumption. Only for the really long-ranged planes are 4 engines needed and these planes are easier to maintain than trijets, which have engines buried in the fuselage or tail.
As a result of all of this, the MD11 is being dropped by airlines in favour of the newer craft. FedEx will certainly buy the majority of the planes and, along with a few other airlines, will ensure that they have long service lives as freighters. Perhaps that is one benefit of MD11 being a DC10 derivative, namely excellence in the freighter mode. Since they are new and relatively modern, they could cause DC10F/MD10 values to plummet. Alas, in so saying this is indeed the end for the MD11.
Hop to it, fly for life!