Back on the F/A-XX, I've been wondering if the concerns about the Navy project running in parallel with F-47 are mostly about software development.
In my opinion, some companies (NG) do appear to have the capacity to begin work on the EMD phase of a sixth gen fighter, yet there have been fears that this is not true. So I've been wondering why.
My basic assumptions are that NG is available (and qualified, competent, etc) to do the airframing and general systems integration, as well as stealth, that NAVAIR is available to do its supervisory part, and that the engines, being derivatives of an existing design, are likely very ready for EMD. Those things considered together pretty much mean that all components are "go" for designing and building flight test articles for much of the Developmental Testing. Sensors are really the only other thing I can think of, but they can appear later in DT, and then get particularly important in OT.
However, the big piece that that doesn't account for, again other than the sensors, is the software for tying everything together. As I understand it, USAF NGAD and Navy NGAD have together been pursuing a single unified software architecture that could be compared to operating systems such as Linux, Android, MacOS, IOS, Windows, etc. I assume that was a long running R&D program with lots of lab and contractor input, culminating in a competition for the NGAD software OS that would be broadly comparable to the way NGAP (and predecessor programs) has been run as a separate competition.
Unlike AETD/AETP/NGAP though, I suspect the software program picked a single contractor a few years ago, and will control costs via government ownership of IP rather than via competition between multiple different products. The gov't owned IP part has been widely reported for years and years, but it's just my conjecture that there will be only one fighter OS-- that is, only one for crewed fighters and their nice sensors, their high end computers, their sensor fusion needs, etc, but of course a different one for CCAs and their very different needs, a bit like desktops and laptops use one class of OS, while smartphones and tablets use another.
I do realize that areas like EW or AI for CCAs are using multiple competing softwares, but in my opinion there will probably nevertheless be only one "Windows" that all the high end sixth gen fighters run on -- infinite programs and apps, but just one OS. So, my theory is that LM is currently building Lindows, or Boeing is building Bindows, etc, and that that eventual operating system will be the software foundation for both the F-47 and the F/A-XX. Hence the entanglement of the two programs, even if NG were to win F/A-XX.
To circle back to sensors, IMO the Navy has probably specified a "value" approach that would essentially use COTS items like the APG-85 or the latest version of the JSF's EOTS, or else possibly the losing bidder's competitors to those, such as whatever Raytheon pitted against the APG-85. But I'd be surprised if they have paid or are paying for any original work on sensors, which in turn would likely make sensors not a developmental bottleneck, although manufacturing delays, spare parts shortages, and reliability issues would still be potential issues. If they have something innovative in the sensor realm, it's probably just easier plug & play for flexibility in the future.