The reason Pilot Photog can be quite confident that the F/A-XX will look like this is that a blended wing body (BWB) design. The BWB is what will be used for the Air Force NGAD (Next Generation Air Domination) 6th generation fighter.

The BWB has more range and is better for stealth.

Other aspects are the need to get rid of the radar reflecting vertical tails and to hide the engine and other parts from radar reflection.

The BWB can still achieve supersonic speed.

The Navy F/A-XX must use shorter aircraft carrier runways while the Air Force NGAD can use long land based runways. This forces other Navy engine design changes.

The other 6th generation fighter designs from Japan-Italy and China do not have all of the US experience with Blended wing planes, flying wings and stealth. This is why most of the published designs for their planes include vertical tails. They cannot go for all of the maximum stealth options which the US is able to use.

The F/A-XX has been in development for 3 years and $1.53 billion has been allocated in 2024. This budget is more than the next gen submarine and next gen destroyer.