I like that theory.

Reading through Wikipedia, Concorde was more expensive to develop than planned, and the expectation was for 350 orders, but in the end only 20 were built. They stopped building them almost 25 years before they stopped flying, so I'd guess it was a combination of factors.

Perhaps the lack of actual orders after initial interest was due to the uptake of fax machines, which would have reduced the interest from passengers and therefore airlines.