I don't know if ATC headsets undergo regular testing or servicing. I expect that is up to individual units. But I wouldn't mind betting that modern sets won't have the longevity of the older models. For example,I have an Astrolite on my desk which I've just cleaned and rebuilt. I admit I managed to destroy the microphone when prising it out of the boom but the set otherwise works perfectly and is tough, robust and the best part of forty years old. I'll be amazed if a modern Sennheiser or Airlite 100 is still around in 2056. Such is our throwaway society.
IIRC, BBC cameramen used to use Astrolites as well. And British Airways across many aircraft types.