Just for comparison the Concorde (which used engines based on a military bomber) used around 5x as much fuel as an A380 to transport passengers over the same di

Just for comparison the Concorde (which used engines based on a military bomber) used around 5x as much fuel as an A380 to transport passengers over the same distance - so there is a lot of room for improvement. Economically I don't think there will ever be a market for the speed alone to command paying a much higher ticket price, but maybe technologies can be developed that will mean supersonic aircraft are as efficient (or more so) than subsonic aircraft.