Gidday,
At the fine old age of 62, still able to instruct on Jet simulators, able in a small way to contribute my so called wisdom to the masses and actually still learning in the process.
Age alone should not be a barrier to anyone doing anything that we are capeable and competent to continue to do.
I found retirement too busy, so took up a full time job to get the weekends off.
As to line flying, why not if you can and the employer is willing, I miss the flying but dont miss the dark nights and storms of the Bay of Bengal one little bit.
There is a chance of a DC-3 being in need of a part time F/O, so I may grumble around as I did in the 60s, full circle on Airline types, within meters of where I first learned to fly.
Old age and cunning is better than some of the alternatives.