Enourmous operating costs, and the fact that FAA wouldn't allow it to fly above Mach .99 over US land meant that on cross continent flights it would be as fast as a B727, so the advantage was killed, it was only interesting for over-Atlantic or over-Pacific routes. A pity, but it sure was noisy. What was a sonic bang between friends? Whoever wants to resurrect the beast must have deep pockets, very deep pockets! Besides, as I've said more than once here, I dislike the idea of keeping vet planes on the air at any cost. However well maintained they'll become riskier and riskier, until a bent undercart or prop happens, sometimes a life or two. Keep historical planes to museums. I have to agree with Miguel. Resurrecting 30 yr+ old technology makes no sense. A truly amazing aircraft but it's time has past. If supersonic, Trans-Atlantic flight was financially viable, someone would have already filled that void.