This year, Delta gained more customers in part because its competitors had to cut flights due to the grounding of the Boeing 737 Max after two crashes overseas.
But next year could bring some uncertainty for Delta, when competitors including Southwest and American bring the 737 Max back into service pending Federal Aviation Administration clearance.
That could bring heightened competition that some have speculated could spark fare wars when airlines that operate the 737 Max work to attract more passengers.
Delta does not have the 737 Max in its fleet and thus did not have to ground planes.
Bastian said “we look forward to competing against the Max.”
"I don't think the Max being out is good for any of us," he said, but added: "The customers that have come over to Delta have experienced the Delta-style service. I expect many of them will stay with Delta."