F-35B or F-35C
The trouble with doing away with the 'Dave B' is that it completely negates the purpose of the F-35 programme.
If the requirement for the JSF had not included STOVL, then the aircraft would have looked completely different, and may well have been twin-engined. The STOVL requirement completely drives the need for a single (humongous) engine, which in turn drives the fuselage shape, and amongst other things determines that there can't be a central weapons bay.
If the F-35 is abandoned - and the USMC requirement may well be not enough to keep it alive - then the entire programme is very obviously a complete waste of time and money, producing an aircraft with design compromises that are suddenly completely irrelevant to its revised CONOPS.
Hence, there will be a great deal of pressure for the UK to "keep the faith" with the F-35B.