Tbh like it or not having an AI flight is of no use to regular international flyers coz the service is average and the price is exorbitant. BA or AA would have been useful but really, how many people from Kolkata regularly travel to those cities and vice versa and would that fill a wide body jetliner (330/777)? I'm sure if it was feasible, BA or AA would have run it. They stopped due to lack of passengers. What fuels passengers is if there are lots of MNC and Big Tech which Mumbai, Bengaluru, Delhi and Hyderabad have but Kolkata hardly has any.