Exponential scientific and technical advancements only happen in the early stages of the large scale adoption of a technology. Von Braun went from launching hand made rockets as part of a rocket club to leading the team that engineered the moon landings, but since then rocketry improvements have been incremental. I think with computer technology we're still in an early phase. Eventually we will reach the limitations of the current silicon transistor paradigm. Maybe something else will take over, maybe it won't.
But sometimes several things come together to lead to a new capabilty. SpaceX recoverable rockets aren't just due to incremental improvements in rocket engines, they're due to improvements in a whole host of different areas - materials technology for lighter rockets, software improvements, better heat shielding materials and frankly new economic imperatives. Those all came together to push us over the edge of a new capability. Maybe the same will happen with supersonic passenger planes.
But sometimes several things come together to lead to a new capabilty. SpaceX recoverable rockets aren't just due to incremental improvements in rocket engines, they're due to improvements in a whole host of different areas - materials technology for lighter rockets, software improvements, better heat shielding materials and frankly new economic imperatives. Those all came together to push us over the edge of a new capability. Maybe the same will happen with supersonic passenger planes.