There is an element of "how do we get from here to there?" in the AF/Navy force planning dilemmas.
Even if the F-35 eventually lives up to its promises in terms of acquisition cost, availability and op cost/manpower demands, it is now so late, and the airplanes it was supposed to replace are so old, that you face the Valley of Death.
For example: every new F-35 that gets delivered takes the support manpower of >1 F-16 or A-10. But today it delivers no capability at all. Even at IOC, given the current availability levels, you need >1 F-35 to generate as many sorties as one F-16.
As Bogdan has noted, F-35s being delivered now need a lot of work to get to 3F. Those updates hog more maintenance time.
The F-35 acquisition overruns have already eaten the budget for F-16 upgrades. Without them, sometime in the mid-20s, the F-16s become useless for anything except a permissive environment - but the USAF can't afford to replace them all by then.
But as I add F-35 squadrons, I have to shut F-16/A-10 squadrons at a higher rate. And then where are my experienced people to man the next F-35 squadrons after 2025, when the new jets arrive?
The Navy has the same issue with the F/A-18C (remember, that's what the F-35C is supposed to replace, not the Super). It has to fill its bucket with Slep'd SHs. But to Slep jets I have to pull them out of the line for a year or more, exacerbating by shortfall.