Quality cables is a recent event. Most cable brands out there are less than five to seven years old. I would not consider any of them old yet. Some of the very oldest MIT music hose from 1985 may be a risk, but has anyone cut then open or tested them to see? The MIT Terminator series only started in 1994 (white jacket); the ones with the grey jacket are only a couple years old at the most.
The original poster did not specify copper cable. Silver cable is another story completely. As well as silver/copper strands like Nordost and others; and gold/silver cable like Siltech. These types of cable should last a lot longer than copper. It is my understanding that silver is still a good conductor when it tarnishes. Gold's conducting properties will be the same a million years from now.