Potkettleblack has it quite correct. There will NEVER be any lack of applicants for ANY flying job. Jets, props, instructing inclusive.
Age has become largely irrelevant; more given the fact that older applicants are likely to be able to fund 500hrs Line Training P2F.
With 500 Hrs A320 / 737 etc aged 45 you will still get hired every time infront of a 20 year old 200hrs FATPL. FACT.
I think that P2F has actually given a ready route to the older career changer. Still with at least 20 years of potential work in them.
I have said it before; my private owner operates 2 business jets and actively prefers older pilots. He finds little in common with the 20 somethings, so the 'grey hairs' get our vote every time. Indeed a 50 year old that had funded 500 hrs jet time would be an attractive proposition. The jet hours are a requisite for insurance and the age means he has other skills to help within our small team.
Please; no one be put off by any you're over 40 cobblers.