Boom can use the Tesla approach by starting with business class customers to prove the demand then moving down the latter to consumers. Tokyo could be a weekend trip if the flight was five hours.
Business aviation is a less lucrative market than commercial, and business-only commercial flights is a market which has almost completely failed to make any profit. In automotive terms, not only are there are a lot more people buying buses than cars, you also don't make a higher profit on the cars either unless you're the interiors outfitter....
https://www.aerionsupersonic.com
So there may end up being other options.
That doesn't translate particularly well to less frequent 55 business class seat flights on most of those routes; even if the flights are shorter the arrival times are probably a lot less convenient for most of the executives.
The all-business class model has struggled to be economically viable even on ideal routes like London-NY. Those economy seats give you a lot more flexibility when the business class seats aren't selling.
(And as ghaff pointed out business travellers /= business class; most people travelling on business have an economy ticket sized budget)
For US and European carriers, it's around 75%. Since the cost is 4 - 7x higher than commercial, most people aren't paying for this expensive personally. Not sure about other industries, but for consulting and tech, the standard is to allow a business upgrade on international flights and not domestic.