The RIAA, itself, doesn't use the net for revenew, or, really, much of anything. What few uses they do have could easily be served through disposable dialup accounts. It is the RIAA member companies, such as Sony (one of the biggest offenders), Arista, Geffen, etc. which are getting their revenue through the net. Unfortunately, no provider can defend turning off Sony as a rational business decision. Your customers wouldn't tolerate it or stand behind you on it. (If anyone wants to prove me wrong, I would very much enjoy being wrong on this).
Generic question related to this: Can ISP's arbitrarily refuse to give service to someone who tries to sign up? i.e. if everyone refused to give Sony service could they sue on some sort of discrimination/collusion charge? Do ISP/ASP/*SP's HAVE to provide services if someone knocks on the door requesting them or can they refuse for any reason what so ever? Any armchair lawyers, who play one on TV, have the/an answer? -Rob