mona lot, the US Age Discrimination in Employment Act of 1967 (ADEA) protects certain applicants and employees 40 years of age and older from discrimination on the basis of age in hiring, promotion, discharge, compensation, or terms, conditions or privileges of employment.
So the airlines can not fire them unless they fail their safety exams.
Couple that with some very poor union decisions in the past, and many American FAs do not have the money to retire at an age where the physical strain of the work coupled with the strains imposed by jet lag would indicate that retirement is prudent.
With European laws postponing general pension age, we appear to be going the same way in Europe.
But never fear,
mona lot; with every sort of discrimination being alive and well in the Middle east, your coffee will still be served by fresh faced FAs from the Far East and Eastern Europe for many years to come.

Who get kicked out as soon as it pleases the company, and without a livable pension.
But that is none of your worry is it now?