At just under 5 it already is, I know a few people who do it. Hawaii is a bad example because its very much a leisure market. They can barely make business class work with recliners let alone a Concorde replacement. That’s why they put their worst business class on the route.

This will end up running LAX-JFK-LHR in my opinion.

Would they be allowed to go supersonic for LAX-JFK?

No, that route is over land.

Ah yes, I should have said 'I see a potential market for faster premium air travel on both the LAX-JFK legs and the JFK-LHR legs within the range of the Boom plane' - you are of course correct that they would not be able to fly LAX-JFK supersonic.

Between PA and LA there are not a lot of populated areas so strearing around them should be possible.

14 CFR Part 91.817, in essence, prohibits anyone from operating a civil aircraft at a true flight Mach number greater than 1 over land in the United States and from a certain distance off shore where a boom could reach U.S. shores.

https://www.faa.gov/newsroom/supersonic-flight