I feel like the best use case is international flights. Being able to cut down the time significantly would be a huge improvement.
Honestly though I think shaving off an hour or two is worth quite a lot. There are many people who have conditions, like claustrophobia, people with knee and back issues or hell just regular people get uncomfortable when you're flying for hours and hours. My last two flights were both almost 6 hours each way and I was incredibly sore and ready to get off. It's anecdotal, sure, but I don't know a person who doesn't feel the same way.
And if those people flew international business/first, they'd be a lot more comfortable and it would likely be cheaper than an SST. The Concorde specifically was actually rather cramped. Certainly compared to today's seats up front in a widebody but even compared to first class seats of the time.For me, an 8-12 hour flight is a bit boring but, honestly, it's not really uncomfortable if you fly business and that's the relevant comparison to an SST.
BA now operates a number of the old Concorde flight numbers (BA1, notably) as business-class only flights on an A318 from London City to JFK, with a fuel stop (and customs and immigration pre-clearance at Shannon) on the westbound flight (due to London City's short runway). I do wonder if Concorde would be more profitable nowadays following that example, seating a very small number in standard business lie-flat seats. (Though maybe one doesn't actually need actual flat seats, given flights are all under four hours.)
LA-NY is a key route for SST but was blocked because it was overland. This was one of the main reasons it took forever to become profitable and also why only two airlines ever flew them, and were virtually given the planes.
Honestly though I think shaving off an hour or two is worth quite a lot. There are many people who have conditions, like claustrophobia, people with knee and back issues or hell just regular people get uncomfortable when you're flying for hours and hours. My last two flights were both almost 6 hours each way and I was incredibly sore and ready to get off. It's anecdotal, sure, but I don't know a person who doesn't feel the same way.
Anything that improves the quality of life is good and when these types of planes are more ubiquitous the prices will drop and they will become normal. See Concorde Mark 2 http://www.telegraph.co.uk/finance/newsbysector/industry/eng...