Although this thread is addressing hip issues and clutching, there are plenty of other lower body performance problems that can affect the driving process in later years. My wife has dealt with peripheral neuropathy for 20 years, which can affect both clutch and throttle legs. I parted with two GTXs with manual steering and brakes in recent years. I started using hand controls for trips out of town, after late effects of early polio compromised my ability to maintain pressure against a strong throttle return spring. Power steering and brakes are a most if using this set up with a vintage B body. My wife had a hip replacement 10 years ago, and her ability to use a clutch is still 100%.
I drove my Peterbilt 379 with a dry clutch and 18 speed for a full year after I started using mobility aids part time. With my situation, the clutch was never an issue, but the throttle was, and clinched my decision to retire.