In-laws are slightly above that age bracket and can do all of those things. FIL drove down through France quite recently by himself.
My own parents are slightly younger however have no issues either with any of those things. My own father is currently re-tiling their roof himself at the age of 69.
What I would say is that both my parents and in-laws had fairly active jobs before retirement, all have hobbies which keep them active (walking, Pilates, FIL golfs, MIL plays tennis and swims every day). They both have small-ish grandchildren whom they see regularly and take out/baby sit. They have always loved travel and have kept up with technology.
I have found a difference between my parents/in-laws vs friends parents, who had sedentary jobs, no hobbies or any interested, who retired and seemingly stopped engaging with the world, and suddenly seemed to age dramatically. Rather than having a new lease of life and time to do whatever they want, they've almost lost their purpose now they're not working.
I'm not stereotyping nor blaming retirement (your parent may have never worked for all I know) but this is just my experience.
If your parent was doing all of the things you listed before, and have suddenly ground to a halt without seemingly a reason, then I would be concerned that something else was going on.
Has this come on quite suddenly, or have they always been a bit like this?