Any airline dropping JFK-LHR and EWR-LHR, as well as JFK-LAX, JFK-SFO, EWR-SFO, EWR-LAX, JFK-SJU, EWR-SJU, EWR-CDG and JFK-CDG. An airline has to be a total jackass or the managment would be on badcrack to drop these routes.
SESGDL, I heard, uncomfired, that DL has suspended ATL-NRT, but only for a short while.
VirginA340, don't forget JFK-FLL/MIA, over 2M passengers a year (and way more when you add LGA, EWR, and PBI to the equation). As for some other airlines, Iberia would obviously be stupid to drop MIA-MAD.
They controled most of the market out of CMH at one point and after the 5 gate expansion is complete, they have claimed 4 of those gates to add to the 4 gates (correct me if I'm wrong) that they already have. After all that, it would be a shame to leave.
Delta's 4 new gates in the expanded Concourse C will be the only gates that they will operate from at Port Columbus. They will leave their current gates, C1, C2, and C2A, and move to the expanded area once it is completed. C1 will be expanded to handle more international departures, and C2 and C2A will be open for any other airline wishing to expand or begin service to CMH.