Space is expensive, because it costs so much to lift loads hundreds of km high. In satellites, what masses the most ? Perhaps satellite "shells" could be built, according to a modular protocol, so that they were "orbiting computer shelving cabinets". The "orbiting cabinets" would contain all the heavy components, including rugged shell, solar panels, etc.. Then, light-weight electronics components could be sequentially orbited, installed with space ROVs, with the old components being removed. The heavy "frame" could be repeatedly reused ?
while i'm at it, on the general principle of "recycling", perhaps expensive structures could be built to be "un-buildable". Rather than build a factory, that 20-years later becomes obsolete, if factories could be built, so that 20-years down later, they could be economically un-built, and the parts recycled ("all the cinder-blocs snap together like legos, and can be reused & reconfigured"), perhaps long-term costs could be cut, and wastage minimized. By biological analogy, bio-mass that is no longer "functional" (alive), is broken down, and all the bio-valuable carbon & nutrients recaptured, recycled, and reused.
