It is sometimes suggested that fuel produced on the Moon or on asteroids could be launched more cheaply to dock with and refuel for example communication satellites in GEO to extend their operating lifetimes (as in orbital station keeping). This has of course to compete with simply launching more fuel from Earth together with the satellite to begin with.
But isn't the economic lifetime in GEO limited more by the aging of the electronics than by the fuel consumption? Hubble Space Telescope was upgraded with new instruments several times and practically worked as a whole series of different telescopes in some respects. If com sats are designed to be upgraded robotically, wouldn't it require much less launch mass to do so than to refuel them in mid-life or launch a completely new satellite? An upgrade mission could even be launched as a secondary payload with another new satellite to GEO.
Isn't it in general more economical to launch the latest "smart mass" that in the end is producing the commercial service, than bulk mass like fuel, if one is to go through the hassle of docking anyway?