Yeah, the Airforce also said the era of dog fighting was gone too back in the late 60's. We all know how well that went don't we.
Technology was the limiting factor of guided missiles, then, as is today.
Technology however, cannot undo what G-forces do to the human body.
Aerodynamics have progressed to the point where the soft stuff in the cockpit is limiting the airframe's potential. Already most 4.5 and 5th generation fighters have computer limitations put onto control inputs, and the airframe cannot be maxed out, performance-wise.
The first nation to put up a highly maneuverable fighter drone, that can pull sustained 15 and 17 G loads, will whip any manned air force, even if they weaponize it only with a shotgun. Understand, even a highly resistant pilot with training can only pull 9 Gs sustained for a very limited time. He comes up against something that pulls another 6 or 7 past him......it's literally the difference between a Cessna 172 and the F-22.