Pretty much what Todd said. There is no incentive to split out a sports package as long as subscribers shell out the $$ after they finish complaining. In order for a model change to happen, enough people need to cut the cable and go back to OTA that the providers see a drop in revenue.
Alternately, a provider that was struggling could choose to do this to increase their share. However, that is less likely because the content providers have all adopted the mafia model where "youse can have the ABC broadcast, but youse also gots to take the ABC Family and the ESPN" A weak provider has no leverage yo break that model and it would need to be initiated art the content provider level.