The pilots union (and by extension airlines) need to establish a pension/insurance category for this eventuality imo.

We need pilots with mental health issues to seek treatment for the safety of themselves and more importantly passengers. The mental health issue may be resistant to treatment or otherwise disqualify them from flying in the near or long term. When that happens, they lose their career.

A robust system for handling this eventuality, much like getting injured on the job, needs to be put in place.