The aircraft has a range on 15 hours, just like the 330 can fly non stop for 17 hours with no pax. It was sold by Boeing as a point to point aircraft and on routes which were not economically feasible on other aircrafts in production. It Seats 250 pax, whih is similar to 757, 767, 330, certain variants of 340 and all economy 321 which can seat 220 and fly them at any range required upto 15 hours which is within range of 95% routes of today and it can do at a lesser cost to the 777 or the 330 or the 767.

The airlines can use it to build routes likes Qatar plans , use them on long thin routes, so Toronto for air India makes sense and also use it on regional routes where narrow body aircraft don't have range like India Saudi Arabia.

Air India bought it to primarily replace 310 fleet, and routes greater than 5 hours and upto 10 hours flying time from India would be where try would he using them and maybe tatl if they think the 777 is not making sene for that route.

Ultimately it's a govt airline and they will do what the babu decides. I heard yesterday they want one 787 positioned in Kerala as the Kerala brigade also wants a piece of the pie.