I'm 56. Until last November I was still doing high impact, high intensity workouts. Then I injured my knee and had my second knee surgery in 8 years. I ignored a growing discomfort in my knee until it became actively injured. I knew better, so I don't know why I was so dumb.
Anyway, no more high impact for me. I do the same weight workouts but instead of high impact cardio I do more metabolic workouts with light weights, kettlebells and Cathe's low impact cardio. I can do plyometrics - they don't bother me at all. The intensity of my workouts has gone down slightly, but I can still get a really good sweat going with the kettlebells and metabolic workouts.