Surely they could be used as storage tanks, instead of living spaces. I doubt they'd be rated, after the stresses of launch, for long-term habitation, but there's going to be ample need for the bulk storage of mass. One of the sad things that is done, is the jettison and burning of trash; perfectly good organics and mass that might be someday useful in orbit, when the technology is developed to make use of them. Then the containers themselves could be used as raw material for some hypothetical future process.
Whether it's worth the investment is another question entirely, though the existence of a tank full of vacuum-dried sewage co-orbiting the ISS might inspire some thinking about what to put it to use for.
The investment, unfortunately, would also have to include the cost of periodic reboostings, keeping it all fastened together, keeping it balanced along a thrust vector, and several other considerations. It could get very expensive to maintain that orbital junkyard as a future investment, which may or may not even pay off.