cost was a big factor but not just maintenance
After the france crash, there was new concerns about engine safety at takeoff, a 2 engine plane can lose half its horsepower one engine out of 2 and still take off, whilst 4 engine planes often need 3 engines aka 75% power available. The problem with concorde is tho the 2 engines either side are very close to each other and as such damage to one engine can spread to another very easily as was shown in the france crash, and its quite possible concorde would have had to rectify this moving onwards which would have cost a lot of money. I expect this was a factor.
Biting the hand that feeds IT
