That’s a poor response. Major engineering advances that nobody sees coming are exceedingly rare. By the time an advance is close, it’s usually apparent to other engineers. For example, Samuel Langley’s unmanned engine-driven plane flew seven years before the Wright Flyer. It was quite clear by the late 19th century that human flight would happen and we had a pretty good understanding of how.
Will we have supersonic commercial travel at some point? Probably. But that’s not a very interesting statement. Are we close to supersonic commercial air travel and do we have a concrete idea how to get from point A to B? That’s the interesting (and very different) question.
(That is not to say I think Boom will or will not get there, I havent’t studied it closely. But I’m an aerospace engineer by education and history is littered with failures in this space, and progress since the 1980s has been grimly slow.)
