Serious question, other than Muh Stealth, what actually keeps cold war era jets from just being upgraded with modern avionics and loaded as low-cost missile trucks or converted into drone fighters? They have kinematic performance that is still very much relevant. In fact a lot of 4th gens are comparatively underpowered and wouldn't be able to catch them.

Anyway I would like an unmanned cruise missile in the form of an English electric lightning loaded to the gills with bombs, fuel tanks, and an automatic guidance system.