One of the main justifications for the F-35B over the F-35C was that, using STOVL, it would allow the RAF to maintain currency more easily whilst not operating often from the carrier.
If the RAF squadrons go away that justification goes away (even if the RAF provide pilots to the RN squadrons they will presumably do so for full tours).
Given the greater range and weapons load of the F-35C I would presume the case could now be made to fit the carrier with a catapult now and either expand the capability or reduce the number required to perform the same task?