we're talking about a largely unproven airplane after all ...
large parts of which still exists only on paper ....
I still believe that if the costs become astronomical, then we'd
can simply get something else ... eurofighter anyone ? ....
even the brits have threatened to get a navalized version of the
typhoon for their QE class carriers if things doesn't go their way
in the JSF project ... I don't think we're committed in anyway to a
purchase, other than the sum of money we've paid .....
hmm ?
in what sense is it unproven and large parts of which it exists
only on paper ? its flying, its in LRIP at the moment. A version is
proceedingly nicely on the development timeline, C/carrier version
i m not certain but the B version is the one thats having alot of
problems with the lift fans/blade issue.

i think one must consider the threat scenario first before we
write off the F35. first you have the Su-30s/35/PAK-FA coming up on
the radar screen. the F35 is designed to counter and achieve
superiority over these platforms.
currently there are no western platforms equivalent to these.
the Eurofighter typhoon comes close, but AFAIK, the targeting
systems arent that good and the avionics pod they are developing
for it seems to have been delayed. The F35 comes with the
equivalent of a Sniper pod intergreated.
maybe can think of it this way ? u pay roughly 60 million for a
typhoon, but if you get a F35, is like getting a typhoon several
tranches down in terms of upgrades. capability of the F35 is
superior in the sense it is going to have the Off boresight LOAL
system, 360 degrees DAS and superior thrust in comparison to the
eurofighter.
plus u cant discount stealth. it could be the real effect
multiplier. stealth is really useful if its going to be a first day
strike mission to take out the other sides air assets.