Not really sure what they expect to get out of a cost review, though. The AFO replacement can maybe refine requirements, but what makes it expensive is it's comms and connectivity and survivability requirements. It doesn't exactly have gold-plated toilets. F-35 costs are already coming down as the production process matures. It's not like they'll just agree to take less money for the work - government contracts don't work like that. If you got what you ordered, you're obliged to pay what you agreed to pay. This isn't like stiffing a plumber; Boeing and L-M have their own lawyers and the USG wouldn't have a legal leg to stand on.
Another interesting point is that we're taking delivery of airplanes that were ordered 10 years ago. Look at the AF tailnumbers coming off the line- the first two numbers are the year it was ordered/paid for- they are all 07-09 numbers. We're in a lot deeper than people seem to think.