Building supersonic passenger planes was never a technical problem (see Concorde), the problem is: they are too expensive to operate to be profitable. I bet this thing will never see any commercial use.
It is a technical problem bit still with very hard limits as to how much energy it will cost minimum to accomplish. You still gotta push through the air at higher speeds which takes a lot of energy/fuel. Best case is they go high enough to avoid a lot of the air, but you still have to get yourself up to that altitude through the air to start with.
Airplane cost to operate is fuel consumption, and, by the laws of physic, aerodynamic resistance scales as a square of speed, so you can’t really work around it unless you invent some new laws of physics.
Your conclusion is really a false dichotomy.
The square of something very very small (close to zero) is negligeable : thus subortibal hop (Concorde was flying at 18km altitute for example).
One of Concordes problems was also that it was not that much faster for how uncomfortable it was. For London -> NY, You were looking at 7 hours in a luxurious business class vs 3.5 hours in a crammed noisy shaking metal tube for twice the price.