if Boeing(?) think that by shoving the RN a knocked off 12 aircraft fleet of F/A-18F's - that will, realisticly, mean that that the F-35 programme gets cancelled and the the F/A-18E/F/G will stay in production for the next 15 years and take a good slice of would have been the sales going to F-35, then they'll find a way of making it affordable.
coz thats whats on the table - if the RN/RAF decide that actually, FA-18E/F/G with some stand-off weapons can do 90% of what JSF can do for 75% of the money and do it before their shiney new carriers turn to rust/the GR4 fleet starts falling out of the sky, then the export market for F-35, and the USN's already lukewarm interest in the programme will evaporate.
continuing the JSF programme as F-35A only probably isn't credible - and Boeing know that as well as the subsequent F/A-18E/F/G sales they'd make if JSF was cancelled, they'd be flogging new-build F-15's like hot cakes.
its called a 'loss-leader' at Tesco, and Boeing aren't stupid...