If properly lubricated many cables last almost indefinitely. I would not
replace one unless there were signs of wear or stiffness. What was the
survey for? Your own personal information or pre-sale information? If
pre-sale, I'd simply pass the info onto the potential buyer and try to get
his agreement that there is no justification to replace anything based on
age. There is no end to that drill, light bulbs, throttle cables, engine,
transmission, cutlass, etc ad inifinitum!

Don Dando