Concorde made money for British Airways in every year it flew. Originally, however, they had to return 80% of any operating profit to the UK Government in exchange for a 'Condorde Subsidy'

After BA had been privatised they bought themselves out of that agreement, ending the subsidy but pocketing the profit directly. They then proceeded to operate the fleet for another 20 years.

So, in a British context, on an operating basis Concorde absolutely was economically viable. On a program basis, considering all the development costs, it was not; but then again the Boeing 787 program is > $30 billion in deficit right now and is unlikely to ever clear that.

I think this lesson has been learned. After making losses for a while, British Airways did the research and found that people who were willing to pay for the Concorde's pricier tickets were actually willing to pay substantially more.

After BA upped the ticket prices and the wealthy customers just kept paying, the service quickly became profitable for them, and remained so until the crash.

For any new entrant to this market, it will need to remain an expensive niche.