An unsung part of the economic disadvantages of supersonic is how often the value of speed in the connection of two cities is not anywhere near even in both directions. Say we are looking at London-NY. The flight takes 3 hours, and the time difference is 5 hours. If you are leaving London, this means you can leave at a reasonable time, and have plenty of useful business meetings in New York: Much better the subsonic flight. But what happens when you fly in the other direction? In practice, it's 8 hours. So leave NYC at 8 am in the morning, and by the time you are at an office in London, the workday is over: Far less valuable for an executive than the other direction. Thus, the price differential over the regular flight in one direction is very different than in the other.

A supersonic jet with concorde-like economics in supersonic routes would be usable if it could fly subsonic at a competitive price on the way back, but that's not how physics works.