Much of modern life has improved since the 1970s. Not so air travel: Getting from New York to London takes roughly as long now as it did in the days of disco. Could that be about to change? Nearly 20 years after the Concorde made its final touchdown, supersonic flight is once again becoming a tantalizing possibility. A handful of enterprising companies are now manufacturing next-generation jets that can exceed the speed of sound and dramatically reduce flight times. Warren Buffettâs NetJets just ordered 20 of them from the startup Aerion, at about $120 million apiece. UBS reckons the total market for supersonics could reach $340 billion by 2040.