Boom supersonic airliner will basically be a fuel efficient updated version of the Concorde. I think the main reason passenger jets aren't much faster is because fuel efficiency but also because of sonic booms. You can only go supersonic over the ocean without causing noise pollution issues. Once quieter supersonic, fuel efficient aircraft hit the market, things will be better. Longhaul flights will be drastically cheaper because airlines will be able to fly more legs with a single aircraft and it will take less time to get to your destination.