I would even go out on a limb and say that someday supersonic flight will be so relatively near to the economics of subsonic flight that it's often the norm. (In the same way that, in the US, you don't see a lot of props on regional flights any longer.) [ADDED: And yeah much higher drag at higher velocities, etc. but let's stipulate "tech."]
However, it's a huge economic hill to climb. Long haul flying is already pretty comfortable if you spend the money. Even on United which has been upgrading domestic routes. Of course, faster is better. But lie flat seating, decent food, and even mini-rooms go a long way towards making lengthy flights comfortable.
So you basically have to get close to those price points, which is the high end of the volume market. A few hours aren't worth that much even to most relatively wealthy folks.
Those aren't the high-end of the volume market. They're the private jet market which is circa an order of magnitude more expensive and correspondingly smaller.
However, it's a huge economic hill to climb. Long haul flying is already pretty comfortable if you spend the money. Even on United which has been upgrading domestic routes. Of course, faster is better. But lie flat seating, decent food, and even mini-rooms go a long way towards making lengthy flights comfortable.
So you basically have to get close to those price points, which is the high end of the volume market. A few hours aren't worth that much even to most relatively wealthy folks.