Or, as the DoD learned at the very end of the F-22 production timeline, don't stop making jets when their cost hits the nadir. F-35 cost per airframe is already down to where the last batch of F-22s were before the line was terminated, and will drop further. The brutal truth is that the US will go "all in" on F-35 because the real value is getting cost per flying hour, through-life, down to something reasonable - and you can only do that when supporting high mass, to make savings in bulk production of parts etc.
FWIW I don't believe the USN has even the slightest vector (running, walking or crawling, for that matter) away from F-35C. The interoperability with 4th Gen platforms is to ensure the new jets don't make the old ones - jets with many usable hours left on them - obsolete. Ensuring F-35 can "talk" to existing 4th Gen fighters (and others) enhances their capabilities, makes perfect sense and acknowledges/mitigates the delay in bringing desired numbers of F-35 to the fleet. "Delay" includes unplanned (i.e. Program delivery delays due to concurrency) and planned ("we simply don't have the cash now but need to fill the fighter gap).
Interoperability across 4th and 5th Gen is/was an inevitability and isn't limited to the USN either and, to suggest that it's being done to make up for a lack for F-35 capability, is disingenuous and (frankly) wrong.