Southwest still has a hub in ATL and a lot of connecting pax through ATL.

Strategically, JetBlue should have added the BOS-ATL route in the early stage of the AirTran-Southwest conversion, along with adding ATL-FLL. Southwest might have not converted the BOS-ATL route to it's own metal if JetBlue had gone in, and had as much ease to build a frequent flier base on the route.