....We may see a return of supersonic flight within the next 15 years.
Thanks to better understanding of how sonic booms are generated from the shape of the plane and definitely way better jet engine technology, we may be able to very soon build a business jet seating 10 passengers capable of flying at Mach 1.6 at ranges up to 6,000 nautical miles with just about no sonic boom audible on the ground even when the plane is fly at Mach 1.6.
How is this possible? First, aerodynamic research using computational fluid dynamics have identified ways to minimize the pressure wave buildup that causes the sonic boom in the first place with very careful shaping of the fuselage and wings. This makes to possible to effectively eliminate the audible sonic at speeds up to Mach 1.6. Secondly, modern engine design using variable cycle engines (GE Aero Engines successfully tested the technology on a engine intended for the Advanced Technology Fighter program that resulted in the F-22A Raptor) means high-bypass turbofan fuel efficiency at subsonic speeds but can change configuration to fly at supersonic speeds with a small amount of reheat (afterburning) to keep fuel consumption and harmful exhaust missions as low as possible. Finally, by keeping the top speed to Mach 1.6, it means less structural heating from flying at supersonic speeds and less need to run a lot of reheat (afterburning) on the engines, which means lower fuel consumption and less need for expensive high-temperature rated stainless steel or titanium structural parts like those used on the Concorde.
I've read companies that sell fractional ownership of private jets such as FlexJet or NetJets would immediately buy 50 of these supersonic business jets once approved for production. The ability to fly from New York City to London in around 4 hours as opposed to the circa 7.5 hours with current jet airliners makes it very attractive to business customers, especially since many live by the motto of "time is money."