As noted on another thread: For the time being the UK plan has to say F-35B, because the official US plan is that there will be no other CV jet in production after 2015, and the Super Hornet starts to retire in 2030.
However, in many ways the UK, RN and Marine JSF plans were propping one another up. The Marines were pointing to the UK and saying "We can't bin the B and leave the UK with two big grey cruise liners" and the USN thought that as long as it was paying for the B it had to go along with the C.
Now, it is becoming legitimate and almost respectable to start asking that old dodgy question - "Why does the Navy's army need its own air force?" - and if the answer is "it's a nice idea but it adds only xx per cent to the capability of a joint force" then Marine TacAir goes, and if that happens the Navy will scrap the C in a picosecond.