The USAF said they flew something. The reporting is making it sound like this must be *the* fighter design. That they flew *something* isn’t what I’m discounting. What I’m discounting is that what flew was a “prototype” of a 6th gen fighter. It could easily just be a small scale demonstrator to test a few concepts. For example, Japan flew the X-2 as part of their program to develop a fifth generation fighter. Does that mean they have a fifth generation fighter design already flying? No. The X-2 isn’t the design that’s mean to be developed and procured, it’s just a technology demonstrator, even though it’s part of that program.
Given the size and significance of a mainstay fighter program, there’s no way the Pentagon would be able to classify such a program if a design has been locked down and a contractor has been selected, for budgetary oversight reasons. At the very least some decision would have to be announced and documented that a program is preceding with a particular design and a particular contractor. That’s how this process works in the US. If there’s no news of a design and contractor being committed to, then an actual fighter meant to be a production design does not yet exist.