Hi John.
Firstly I should the text is not mine, it is the opening of the linked article, which alerted me to the others which is why I used it.
The question of whether the F-35 is essential is a moot point. The performance is only equivalent to that of the F-16, and the value of it's stealth performance against recent radars and SAW is increasingly questioned. The avionics and sensors are leading edge, but can be added to older platforms.
There are many in the USN who would be happy to stick with the FA-18 for many years until a suitable 2 engined replacement could be obtained. The price of the F-35 against the F-18 means far fewer can be bought, bringing into question the number of carriers.
Similarily, there are those in the USAF who would prefer to buy more F-15Es and reopen the F-22 line for AD aircraft.
The only force wedded to the F-35 are the USMC - but their Concept of Ops may be changing so that operating from the main USN carriers may be the logical way ahead, in which case commonality of aircraft seems sensible.
So, no, whilst the F-35 may be desirable, and perhaps now even politically uncancellable, the case that is essential is not indisputable, and as Sweetman et al demonstrate, is not undisputed.