That sucks, and assuming the tech hasnt been kept up with nor advanced it probably isn't coming back.
This does disprove some theories and ideas though.
It isn't. You know how the Apollo Program contains literal lost technology because one of the materials in the Saturn V rocket was classified and the plans for it were destroyed in order to prevent the Soviets using it in their ICBMs, and the factories that made it were dismantled, and the factories that made the machines that go in the factory that made it were dismantled? Well, it's the same with Concorde.
We can still do supersonic flight. In fact, supersonic flight has been a thing since the 1950s. It was fairly easy, once the jet engine was developed, to go faster than sound. The problem is this. Supersonic flight is really stressful mechanically on the plane, the engines, and also anyone and anything on board. Building a fast jet fighter was easy compared to Concorde because, say, an F-16 is small and fighter jocks are used to being thrown around so much they have to be strapped in. So you can make the cockpit as cramped and utilitarian as you like and outfit the pilot with a pressure suit (as they did in the SR-71). Basically, as long as the pilot doesn't black out or have their eyeballs explode, it's just fine.
Concorde, on the other hand, had to be able to do all that, and have 100+ passengers and a full crew able to kick back and relax and not be strapped in ultra tight to carbon fibre reinforced seats, wear pressure suits, and gasp for breath. To get up to Mach 2 without using absolutely stupid quantities of fuel, they made it so the cruising altitude was 60,000 feet (higher than the ceiling of most contemporary jet fighters), thus less air resistance. But that also means less lift because of the thinner atmosphere. It also means that it needs to be able to accelerate harder than a standard airliner could hope to in order to get to that altitude in the first place while still being comfy for the passengers, which means it has to be built to incredible G-forces even though it's not doing high stress manoeuvres.
Even when cruising the plane is physically shorter because of the forces loaded on it than otherwise. You know how the SR-71 Blackbird's fuel tank is deliberately leaky at ground level so it doesn't burst at high altitudes? That's Concorde's entire fuselage. There was a story that someone dropped their hat while boarding and it fell between two of the bulkheads, and when they landed they found it had been embedded into the structure of the plane. Think how excessively engineered it had to be to basically move things at spy plane / interceptor speed but first class comfort. It basically required a whole parallel industry to produce. And that industry is all gone now.
To bring it back, they would need to pretty much start a whole industry from the ground up. The workshops and factories and assembly lines at Boeing or Airbus or Lockheed Martin just aren't set up for this. They're set up to do big slow planes, or small fast planes. Big fast planes are something else entirely.