[ulfw]

Over water isn't too bad a problem as many major routes (e.g. US - Europe, US - Asia, US-Australia, Asia - Australia) are over long stretches of ocean.

But will the range be there? Concorde was severely range limited, which somewhat defeats the purpose of faster travel (if it only works on medium length routes).

Cutting a 14hr SYD-SFO flight down to 8.5hrs is just more impactful than cutting a 7h LHR-JFK flight down to 4.2 (when taking into consideration significant time at the airfields for taxi, boarding, security checks etc)

Concorde didn't have the range for long haul and once you need to land to refuel you lose all time savings.