electrostatic and capacitors... more about the capacitor though
Everything degrades over time, the only question is how quickly.  Electrolytic caps tend to degrade faster than ceramics and film caps. One mechanism is evaporation of the wet dielectrics, which causes loss of capacitance.  Parallel plate air dielectric caps like in the old tuners will last a long time.  Everything is dependent on environmental conditions and how the caps are used in the application.  High ripple current, high temperature and high voltage stress can lead to shorter life.