Delta was not always the airlines they are today. Delta used to have routes that lost demand in the Slump of Demand (2012-2015). But, Now demand is rising for these routes again and I think that that Delta should start up these routes again.
1. JFK-DEL (Delta)
Delta used to operate JFK (New York) -DEL (New Delhi) but than downgraded the route to have a stop in AMS (Amsterdam) and operated a Fifth Freedom route between AMS (Amsterdam)-DEL (New Delhi). Now, if any delta flyers want to fly from New York to New Delhi than they route them through AMS on the Delta flight and from AMS-DEL on KLM with a well timed stop of 1:45 in AMS. But, Now the only airline that operated JFK-DEL direct is Air India whose service and seats are borderline Criminal! If Delta would operate this flight with it’s 777-300. It would be a real step up!
2. JFK-VLC (Delta)
Delta operated JFK-VLC from 2009- 2012 as a seasonal service with it’s 757-200. They ended the route because the demand didn’t justify the effort Delta into it and Delta wanted to get out of the European Seasonal Market at the time. But, they were always making a profit! Now, The demand for a direct flight to Valencia from New York is now higher than the original demand in 2009. I chose Delta as the most likely candidate to restart a flight because they’re the most likely to venture into a seasonal destination.