Look, there simply isn't any point - the saving in time doesn't justify the development cost. No-one flies from airport to airport, there are connecting flights, ground holds, appalling surface transport problems to overcome. London to NY, LA to Tokyo, great. But Oxford to Pittsburg, Palm Springs to Pusan, how much time are you going to save overall by doing one leg of the journey in half the time? Ooh, about 12%. Worth it to a very few, unquestionably. But to about 97% of the travelling public, it's not worth it. Just cos you cross the Pacific in 5 instead of 9 hours, you're still going to have a night's sleep at the destination before going into that meeting. Or if you're on holiday, if there's any difference between price (subsonic vs supersonic), you'll take the slower plane and have some extra spending money at the destination.
Anyway, Boeing are the ones who insist that point-to-point is the way to go, and they're building hundreds of 767s and 777s to prove it. Even if they build an SST or even the Sonic Cruiser, those planes will never turn up on flights like Glasgow to Philadelphia or Nice to Atlanta. So do the public want lots of frequency on smaller planes at the most affordable price, or expensive SSTs with connecting flights in CRJs / 737s, with stressful and time consuming connections at congested hubs (which invalidate the time saving anyway)?
PS You guys are underestimating the sonic boom. There may be a way to trick nature but this a very basic law of physics we're talking about and it won't be overcome in our lifetimes. If there is another SST built it'll only fly above Mach 1 over water.
fly Saha Air 707s daily from Tehran's downtown Mehrabad to Mashhad, Kish Island and Ahwaz