I feel like the Cayman ball would be the closest analogue to pickleball. That said, Matt's point is well taken and forward tees and golf carts and such things make golf on the current courses a perfectly enjoyable time for the elderly. So a pickleball analogue isn't really needed, at least not for the same reason.
But maybe a limited-flight ball (and courses) still would make sense for other reasons? I don't know. Pitch and putt exists on a very small level, but I could imagine using a limited-flight ball like the Cayman ball to turn a par-3 course into a full-length course where you could hit all your clubs. Strictly speaking, the Cayman ball itself wouldn't quite do the job because, I believe, off the driver it would go about 180 yards. But something like that could work.