Did I really start this thread 5 years ago?!??!!?
In answer to your question:
When her (whoever "her" is) to have sex on camera is no longer there. And that could be 21, 31, 61, 91.......whatever. There is nothing worse than someone in this industry for the money and nothing else. It shows in her work. Nadia Hilton had a body that most women could never dream of. I know she "Found God" and is now super religious but if you watch her old stuff she looked like she was told her parents died just before going on camera. Then we have someone like Brandi Love who will be 45 in a few weeks yet looks stunning and makes girls half her age look inadequate and she still fucks with all of the passion and desire of anyone out there. Julia Ann will be 49 later this year and while her body is not the same as it was 10-20 years ago (some firming up wouldn't kill her) her desire and energy are there and as long as it is keep going!
As for you...............I have met you several times at shows. Not within the last 5-ish years, but I have. What I saw was a body that just screamed for sex and lots of it and as hard, dirty, passionate, steamy and kinky as it gets. As long as you enjoy what you are doing - keep doing it. Keep showing off a body that is amazing with breasts that just ache to be sucked and fucked (And this from someone who prefers smaller over bigger).
We all hate to see athletes retire then come back and retire then come back and so on. As long as the passion is there and you look decent - keep doing it and don't let age be a factor. When it is time for you (or anyone) to walk away you will know. When your social media followers goes from 5-6 figures to 3 figures that is a sign. When your videos no longer sell - that is a sign. Until then, keep doing it and enjoying it and getting paid to do what you would do for free.