This is somewhat selective. For private sector aviation, we could have had “THEN” represented by the Concorde. “NOW”, no true successor.
I would take exception to the Concorde being private sector, as it was HEAVILY funded by Great Britain and France. It is more like the Space Shuttle than a 747.
The only reason the Concorde didn’t evolve was government (and activist) intervention. Allowed to evolve, airliners would all be flying the Atlantic in 3 hours today. BTW- there will be a corporate (private sector) supersonic jet within 3 years.