American aero companies should have considered taking a page from Barnes Wallis's book and designed a relatively low-speed SST, in the Mach 1.5 range or so, first. I guess by the early Sixties they figured their transAtlantic competition would already have a Mach 2 passenger jet to offer the public and that they had to leapfrog past that. But I'd think that by 1960 they'd have a lot of experience with relatively low supersonic speeds thanks to military fighters and planes like the B-58 "Hustler" bomber, and so whipping up a suitable passenger plane much sooner than the Concorde could come to market would get their foot in the door sooner.
More to the point, around Mach 1.5, the thermal heating in the shock wave is about the right amount to raise stratospheric air to temperatures comparable to those prevailing here on the ground, so either no unusual air conditioning would be needed or at any rate it would be modest. Still more importantly, the temperatures the plane would operate in would be similar to those normal airplanes experience and so standard materials could be reliably used. The aerodynamic compromises between decent supersonic and acceptable subsonic performance (for acceptable takeoff/landing conditions) would be less than for the faster planes too.
The joker in the deck is that while both airframe performance (attainable lift/drag ratio, that is) and engine performance worsen as you push the top speed higher, they don't do so in direct proportion to speed. So if you can make an engine and airframe that can go at Mach 2, it will use more fuel per minute than one that can operate at Mach 1.5, but not 33 percent more, so you wind up with slightly better economy at the faster speed--assuming everything else stays equal which has been pointed out here is not the case. You need a heavier airframe to go faster, which also complicates takeoff and landing. But there is that economic temptation to pioneer ever-higher speeds, which would also reward whoever gets there firstest with the mostest with pre-empting market share.
In hindsight, clearly Concorde was too big a step forward for its day, and given that today there are no SSTs flying for anyone (unless the Russians revive theirs, but I gather those Tupolevs were grounded long ago, not long after they launched in fact) perhaps the time has come to revisit Wallis's modest proposal to begin modestly. Certainly a Mach 1.4 transoceanic liner would be very noticeably faster than anything anyone else has to offer. Given that today aero firms have decades more experience with supersonic military planes, lots of advanced materials, supercruise engines, etc, it ought to be doable as a private venture.
I don't say that it would necessarily be economical, not even sold to a premium market. (Perhaps it would be better to invest in high passenger volume and aim for a mass market instead).
We also have heard tell here on this thread of commercial supersonic business jets; not clear to me if any of them are actually flying or offered for sale yet. I haven't noticed a military executive jet version for anyone's Air Forces, so that casts some doubt on how market-ready any of these can be as of today. But if a version is sold and has decent success I suppose it could lead directly to at least a small and expensive-ticketed common carrier.