The thing that resonates in this story for me, is that these monopsonies mostly harm producers (writers, musicians), not consumers. The monopsonists keep prices quite low and service quite high, compared to monopolists. It really feels like a problem for Stross, but not too generally for mankind (Stross-fans aside).

Troubles on the producer side might force some producers out, but since this is in the creative sphere we cannot really know which Shakespeare we've missed because he "became a banker".

I do feel sorry for Stross the writer that might have to switch publisher, or the artist who gets .002 cents per download, but hey, my Amazon or Spotify experience rocks and delivers great value.

Other comments rightly add that in the transition from monopsony to oligopsony (: say Apple enters) producers might be able to retain more value, but then again, these producers still have to deal with the middle men. You have this stacked market here where each party would blame the others for not getting his / her 'appropriate' level of reward:

producer (creative, high-risk endeavor, superstar effects) <--> publishing house (makes market, creates prints, less risky endeavor, but has competition in picking winners) <--> *platform Amazon (delivers product, makes userbase, pays per sale: least risk but low added value per sale)