A cramped seat on the Concord cost about 3X more (working from memory) than a roomy first class seat on a 747.
Not many people were willing to pay so much more to cross the ocean twice as fast.
I don’t know if the laws of physics and economics have changed much since then.
The laws of physics are what they are, and at this level what we think they are hasn't changed in well over a century.
Engineering (what I do for a living) is the art and science of making them work for us instead of against us ... the big problem with supersonic flight over populated land is the sonic boom. I'm sure you've heard them ... annoying aren't they? Supposedly, the engineers working on the latest generation of experimental SST have managed to minimize the sonic boom to the point that it might not prevent flight over populated land. Whether or not it will make economic sense is a question I'm not qualified to answer. I seriously doubt anyone else on this thread is, either.