In the 1950s and '60s a number of airlines in the UK and elsewhere went out of business. The Chief Navigator of the Charter Company for whom I woorked told me that " their work would still need to be done... by somebody. The Crews would just have to change their cap badges." He proved to be right.
And that was in the days when hardly any scheduled services were allowed to be operated except by State owned airlines, from a very limited number of Major Airports, often with a State Subsidy somewhere to help.
New aircraft could be introduced with " Our NEW Super Jet is faster than Theirs" . For many recent decades with very rare exceptions all fly at around M.8. And fly at F/L35.0 +. ( That is rather like "just below F/L !0.0 " before we had pressurisation !)
Look at the order books for new aircraft from both A and B which are due to be in service whilst some at least of the present fleets are still young, with many years of service potential. The NEW ones ARE more efficient - but still have to be paid for. The present fleets must have a lower book value. Some will be disposed of, not broken up. They will still need staff.
The only aircraft that I flew which had been bought new from the makers was the Bristol 170 Mk32. The others had all seen service as First Class Airliners with some other Major Airline.!
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