Reality is - nobody really wants supersonic airliners. Too expensive, too dirty, and your route options are nearly non-existent due to noise regulations that prohibit to fly supersonic over like 95% of populated territory. By the end of it's life Concorde was flying half full on most of it's flights. Because including time spent going through security, getting to and from airports you were traveling maybe 30% faster than on normal jets, but for five times the price. I'll look like a massive donkey if supersonic passenger aviation becomes a thing again, but I'll go on a limb and say that it won't happen. Because it's not speed that shrunk the world, figuratively. It's availability of intercontinental transport.