draken55,
A fine question, and only time will tell.
The USAF and USMC have gone 'all-in' on the F-35 Program - do you think they'll let it fail? If I were a betting man, I'd say not. With my polarized view of things, the internet's immense community of relatively ignorant F-35-bashers are akin to all the F-16-bashers of the early 1970s. Personally I think people made the right decision in proceeding with the F-16 program in the face of strong criticism over its cost growth, and in my opinion they're making the right decision to press on with F-35 now.
The LRIP1 aircraft are already flying. If the UK government really wanted the F-35 in Service asap, I'm pretty sure LM would take their money today and we could have F-35s in RAF/RN markings flying in 2-3 years. If the UK government chooses to spend their money on the NHS and welfare for the next 10 years that's their decision, but it's not a failing of the F-35 Program.
Affordability is a completely subjective criterion that every country will have to decide for itself. In my opinion there are a number of scenarios in which you can't afford to not have some F-35s up your sleeve.
Regards,
Single Seat, Single Engine, The Only Way To Fly