What’s interesting about supersonic flight is that there’s been some developments on making supersonic flight more fuel efficient. The F-22’s big strategic advantage is that it can supercruise at Mach 1.5, without afterburners, and although the details are not publicly known, the publicly known facts suggest that it’s about 3x as fuel efficient as the other fighters in the US arsenal. If they can get supersonic flight to be more fuel efficient, and avoid sonic booms (an active area of research for NASA’s X-59 project), and we develop manufacturing capacity for huge amounts of synthetic sustainable aviation fuel from CO2 and water and green energy, then maybe we’ll be at a place where supersonic commercial flights can be both economically feasible AND environmentally responsible. Probably not in my lifetime, but still something I expect to happen in the next century or so.