Just one small step away from going hypersonic.
The engineering needed to make the SR-71 fly without, say, the windows popping out due to airframe deformation during heating, was so difficult that it hasn't been matched by anyone. And it was a two-seater that required in-air refueling with unique fuel. The next big leap (if any) will be suborbital rockets, such as the Starship may do. I'm not going to be an early adopter of those kinds of flights, no matter who builds it, btw. 😁
I have been in a Concord, unfortunately only on the ground.
I think it would be cool if Pan Am got and flew a boom plane.