There is also the related problem of reducing the sonic boom. One of the reasons why the Concorde was so expensive was because there are so few routes that it a

There is also the related problem of reducing the sonic boom. One of the reasons why the Concorde was so expensive was because there are so few routes that it actually makes sense to use the Concorde on. Even today, we can add a few more routes that makes sense (thanks to China's growth), but even then, the limited route options would mean a relatively low demand for airframes, thus an inability to take advantage of economies of scales (which are super important in aviation, since R&D costs so goddamn much).