This is the important bit, and it matters a lot more than some of the anecdata the original post mentioned. Commercial airliners haven't got faster than Concorde, they've got slower. They've also got smaller wingspans and less buoyancy than Howard Hughes' Spruce Goose. As impressive as the engineering accomplishments were, they optimized for the wrong goals; today's airliners might not be as interesting but they are fuel efficient, reliable and don't need to float. And regular people fly on them, regularly.

The billions that gets spent on making aero engines 1% more efficient every year might not be as glamorous as Concorde, but cheaper tickets for the general public (and satellite internet in BA1 for those senior executives rich enough to have previously considered Concorde on that route) actually delivered better outcomes.

If instead of looking at progression in maximum speeds one looks at how much people fly, we're in a phase of acceleration.