They could probably make knockoff LaserJet IIIs, but nobody wants enough to fire up an entire line.
I'm sure the same factories could make zero-margin laser or inkjet printers, but why target a shrinking, obsolete market when you could use the same employee expertise to build things for growing, high margin markets?
I'm guessing buggy whip and carriage bolt manufacturers charged crazy markups for 10-20 years after the Model T came out. I think we're witnessing something similar (especially for inkjets that target document sized printouts).