I remember the promise of supersonic flight. When Boeing designed the 747, they put the flight deck on an upper level so that that the nose could be hinged open to load freight. The expectation was that supersonic airliners would replace the 747 on long haul flights within a few years, and the 747 would live out it's lifespan as a freighter. The Concord proved to be expensive to operate, too few were built to recover the engineering costs. Boeing's request that Congress underwrite engineering costs on an American SST, was denied, the mock up was sold off for scrap and lived out it's life in a hanger in Kissimmee Florida. The Russian SST, had engineering issues, and the same high operating costs and was taken out of service after a few short years.
Demand on long haul flights was for cheaper seats. And that is what we have. Smaller planes, with two engines because they cost less to build and maintain, smaller seats, but lower prices.
There are periodic reports of people trying to design a supersonic business jet, something that could morph into a small supersonic airliner. But none has made past prototype and testing.
What killed supersonic travel? A lack of development funding and a demand for cheaper seats on longer flight. We could do it, but it would be expensive.
If you could go from New York to Paris in 3 hours, would you?