The SST (nobody ever referred to it as the "2707") was a "Hail Mary" attempt by Boeing to keep its commercial aircraft division afloat. It was always seen as a joint civilian-military spec project anyway; it was clear that Boeing's production of heavy bombers was over and Douglas and Lockheed were eating Boeing's lunch on heavy transport planes, so they wanted some "look at me" product that would attract enough US government R&D money to keep things going.
The 747 was just into big time production and Boeing was going through a giant "learning curve" reduction in employment, especially in the engineering fields; Seattle-area employment at Boeing fell by something like 75% between 1968 and 1972. The "Boeing Bust" got so bad that some people put up a famous billboard -
By the time Concorde was flying revenue pax the oil crisis and environmental awareness had fully taken hold and it was clear commercial SSTs were relics. When the Soviet Tu-144 crashed in Paris (1973) it was all over for the breed. By that time in Seattle, Boeing was turning around and ramping back up; the SST/2707's demise was not thought about very much.