My laymen guess is that unless your satellite electronics get fried by the particle storm of a solar flare not much happen in space. As long as the power source (solar panels) works and you do not need much fuel for repositioning like in low earth orbit, what stops a well built satellite? (sorry if I am too naive/ignorant)
Batteries can only take so many charge cycles, PV cells get pelted by alpha particles and micrometeoroids. Essentially, "wear and tear" is what eventually kills most spacecraft.
