Options are the key though. Never force anyone, it must be their decision.
That is the key. My father missed seeing a cyclist (didn't hit him) and frightened himself into giving up 3 years ago at 85. I think he gave up too soon, but it was his decision and I did not want to interfere. Parents live on a good bus route (every 15 minutes) and use a taxi to get home with their main shop. Dad looks on the brght side as he is spending a lot less on taxis than he did on running a car. FIL had a minor bump and gave up at 85 (ish). A friend ended up having terrible rows with his father after a bump and confiscation of car keys.
Counting ourselves lucky on this one.
Hoping I have the wisdom to give up at the right time but not looking forward to it.