HUDs are ancient history. They have been around for decades and JHMCS has been around on the military side for over a decade. I'm honestly surprised some level of HoloLens 2/Magic Leap 2-esque AR hasn't been demoed yet for the civilian side.
That would certainly be useful for enhancing situational awareness, particularly for TCAS. I can imagine a floating red circle around a conflicting flight with a line extending out in the direction of flight (which is rather difficult to judge by sight alone). Too much would be distracting, of course, but I can't see any reason why it couldn't be developed with as much care and testing as traditional avionics are.
