I don't want to suggest I have any idea what it's like to be in the OP's shoes, physically or emotionally. Maybe I have a little insight, in that my father was a professional musician almost his whole life, playing saxophone and clarinet, until he had a stroke that affected his throat and he couldn't do it any more, and I saw what it did to him. But everyone's different, and how people are affected and how they react will be different.
All I can say is that for me, I'm already on a downhill path. I've had a couple of reasonably serious injuries and playing with a bass slung over my shoulder is harder than it used to be. But my hands still work, so for now I can still play, and as long as my hands keep working I'll keep playing. Maybe my neck and shoulders will get bad enough that I'll give up the bar gigs and do something low key where it's more acceptable to sit down. Or maybe I'll stay home and noodle in my spare room, record more, try writing more. But music keeps me centered, lifts me when I'm depressed, calms me when I'm worked up, so I'll keep going as long as I can. And when I can't, I guess I'll listen more, expand my musical horizons.
And for what it's worth, when my dad couldn't play any more, he turned to teaching music to school children. He loved it. Gave all his stuff away to kids who couldn't afford their own instruments. Did that for another five years.
