If sequestration bites and the F-35B is cut, I would expect the Navy to take the opportunity to ditch the F-35C at the same time and standardise on the FA-18E/F/G until the X-47 and other lojng range UAVs can fill the attack role.
With China being the threat and with the range of shore based defenses the F-35C looks increasingly inadequate for the role.
That would leave the F-35A for the USAF and other partners - and the RN to ponder........