LA to New York or San Francisco to Honolulu in 2 to 3 hours would be a game changer. You could probably fill a plane at least once a day on those routes for a handsome profit.
Just mind boggling to think of, no trouble finding 100 people daily who want to do a day-trip to California.
In that "hour" I'd watched (IIRC) Fellowship of the Ring, Sunset Boulevard, and—out of a morbid sense of curiosity that I regret—Moonfall.
It breaks noise regs to fly most subsonic 1960s eras jets with their original engines these days, you have to modify them with hush kits, etc.
They forced a lot of these very American jets to be quiet for the sake of just the landing and takeoff phases. I have a hard time seeing that they would/will find a way to make sonic booms acceptable to the general public.
NASA has a research craft aiming to make the noise profile more of a "thump" than "boom": https://www.nasa.gov/news-release/nasa-lockheed-martin-revea...
Regarding LA<->NYC, I think you could make a dent in that market with an all business class flight that flies slightly less than Mach 1 (0.95 or whatever) and has special security screening and baggage handling. People might be willing to pay 30-50% more compared to business class on a regular flight.
Last: Is there a video game like Theme Park or Railroad Tycoon that allows for the simulation of an airline market? That could be fun.