NY Time has a decent article about the past ,present and possible future of the whole JSF program;
In Federal Budget Cutting, F-35 Fighter Jet Is at Risk - NYTimes.com
Software, price, software, helmet , range (?) and software still seem to be the biggest hurdles.
iso 2443 they might be lucky to get 1200-1800, foreign orders more than ever needed to make the unit price low enough to be manageable .
Also the most competition the whole program will likely face will come from the future new stealth bomber (range, payload) for the USAF and the X47 which has started its first on board testing with the US NAVY and will be able to fly considerably further than the F35C.
etc... .