SimonG: And unlike piracy, the increased costs of streaming (which are immense) are not compensated by a few more copies that avoided piracy, but by huge market of used license trading that you can then, again, effectively kill off.
What huge cost ? There is a cost but it's the service provider problem, not the publishers, heck creating and managing a download service with auto-patching, multiplayer support, etc... also involve immense costs.
OnLive failed because they were a game centric service, if not enough peoples were playing using their service then their servers were just taking dust, but if similar services uses existing cloud farms like the ones using Azure, or have at least have other uses for their processing power than just gaming, then it greatly limit the costs.
Another thing is that streaming doesn't just prevent piracy and second hand sales, it also open to the industry all sort of new "opportunities". With it they can implement subscription, pay per minute, charge per "features" (per save slots, per characters), charge for improved graphics and even add unresolvable and unskipable commercials whenever they want.
That's for them a lot more interesting that some few extra copies earn by limiting second hand sales or piracy.