Oh crud Hyperloop finally makes sense to me.
But, yes, I've been in a Concorde (not flown in one) and the seating is, at best, modern domestic--non lie-flat--business class.
I actually think this is something that a lot of modern supersonic travel fans miss. If you're willing to spend the money that supersonic travel will cost you can travel very comfortably. And 12-24 hours of time spent relaxing comfortably is not actually a problem for most people.
There were definitely other problems (the aircraft was a dinosaur, with parts no longer made and a three-person crew; there was no reasonable replacement program on the horizon; the fuel costs of supersonic were hard to justify with the oil prices of the 2000s) but yeah, at some point Concorde's proposition became less and less appealing.
FWIW the biggest supersonic contender these days, Boom, is specifically targeting room and per-mile costs for a modern business-class cabin of 50 people, which is a lot more workable from a business perspective. That being said, the money is not really in transatlantic (where you can sleep for 6-8 hours anyways) but in transpacific, because 12+ hours in a plane is a slog no matter how comfy the seat is.
It does mean that non-stop from LA to San Jose would be right out though. Being conservative and assuming a 300km/h vehicle, you'd want at least 3 stops along the way if people are completely trapped in the vehicle without even being able to stand up, much less relieve themselves.
The bathroom is an obvious problem, and it also ties into problem # 2; the Americans with Disabilities Act. Cars and even minivans are not compliant with ADA without very expensive modification. Airplanes can afford long dwell times and dedicated personnel for people with disabilities, but as designed Boring Company/Hyperloop stuff can't accommodate this in a reasonable way.