If DCA did drop that you'd probably see more of a "hub" in DCA. Regional feed per psa, pdt, rah, awac would still be needed. But you'd see flights like DCA-LAX, DCA-SFO, DCA-CUN etc etc... Also DAL would benefit with it in DCA as Airways, AA, DAL all would in LGA. But in LGA you have the port authority and they are just control freaks... But it would be great to go LGA-CUN, LGA-SEA etc... And yes regional feed would be cut some for "slot" reasons... Also I doubt you'd see the DAL/Airways court case due to them dropping it if either lost the perimeter rule.. Imho