Actually moving magnet and iron cartridges should last as long as their styluses regardless of age. The problem with moving coil cartridges is that copper work hardens. The vibrations travel down the fine wire to the point were they are soldered to a terminal which serves as the fulcrum. The wire will eventually break here. Gold does not work harden so theoretically cartridges with gold coils could last a very long time. I have had two cartridges die this way. It does depend on usage.
Some people believe the suspension changes or hardens with age. I do not know if this is the case. I can't tell that it is as the change would be so slow. I have not noticed this in any of my cartridges. If it is true the compliance of the cartridge would drop over time and your resonance frequency would rise.
Some people believe the suspension changes or hardens with age. I do not know if this is the case. I can't tell that it is as the change would be so slow. I have not noticed this in any of my cartridges. If it is true the compliance of the cartridge would drop over time and your resonance frequency would rise.