An interesting perspective indeed on Concorde's design with respect to its engine placement. I did not think about that immediately but then, with 2 engines in such proximity it is highly possible for catastrophic failure of one to damage the other.
Yes, other planes such as 747, A340 etc. have engines mounted in separate pods but then they are not supersonic. In order to create a design which could undertake supersonic flight it was necessary to create as sleek and aerodynamically refined a design as possible - something which podded engines do not achieve. Concorde's placement of the engines in pairs under the wings was considered superior to the design of TU-144 Charger, whose engines were placed centrally and all of which were adjacent to each other. TU-144's design arose because its engines were so long that they could not have been placed further outward without breaching the leading edge of the wing. Again, the fact that Concorde had the Olympus engines tailored to its needs while TU-144 borrowed its engines directly from bombers was reflected in the designs.
Certainly provisions would have been made for catastrophic failure of an engine but, sadly, this time a calamity occurred. That is not just bad luck, it is about life in general.
My sympathies to all who lost loved ones aboard that flight. May the crew, passengers, other victims and F-BTSC all rest in peace.