Unfortunately the strict regulatory environment within the EU makes operating older aircraft types somewhat more expensive than other, less picky, areas. A quick trip down to Tripoli, Moscow etc shows that!
The huge amount of variables involved in aircraft lease/ownership are starting to pale in the EU and US next to the rising price of a barrel of oil. The rocketing economies of China and India are allowing their governments to subsidise the price of fuel both for aviation and the consumer, thus older aircraft may well be ferried out to those operating areas under wet lease. (eg Fly Globespans 767 operating out of LHR for Air India).
The sad truth is that as airframes get older they get exponentially more expensive to maintain. Less time between regulatory NDT and deep engineering checks are somewhat offset by cheaper spares, known expertise technically and various other factors including an established trained operator base for the type.
Unfortunately, in the areas I fly, fuel IS the crippling factor and aircraft will be laid off/leased based on those variables. The airbus fleet benefits from commonality of both piloting and engineering which helps and the 777/787 tie up shows that Boeing, from a piloting perspective, is going that way as well.
You would be surprised to know how much some stick monkeys understand about the economics of aircraft operating.
