FWIW, you can fly nonstop LAX-DCA today on AS. I realize no other airline can offer this service, but it is possible. Ditto with SEA-DCA. SFO-DCA would be nice, too. UA applied but lost the application to a carrier flying a different route, I think SLC-DCA on DL.
True, AS has a single daily flight to DCA. Nobody is allowed to fly LAX-LGA nonstop (except, of course, on Saturdays). I'm not talking about a single airline flying a single daily flight - I'm talking about allowing any airline that wants to with sufficient frequencies to be useful. IMO, allowing more nonstops from outside the perimeters would be a much better use of the scarce resources of LGA and DCA than permitting US and DL to accumulate enough slots to run connecting hubs at DCA and LGA. I understand that some US and DL constituents might disagree.