I also think that 20 years from now showing up to the fight with nothing more advanced than an F-18 because the F-35 went a bit over-budget and got scrapped, when the bad guys are flying J-20 or PAK-FA will be a really rather bad and short-lived idea.
Spiffing! I'm sure the F-35 will be wonderful one day, ditto the 'B' STOVL job; but we seem a long, long way past the "cheap replacement for the F-16 "!
More F-22's required....