IAD-NRT flights are under consideration now with the Dulles expansion. UA was prob. waiting for the added flights to help feed these flights. It also has to do with aircraft availability, and with the 777's unable still to fly trans-Pacific flights, the only alt. aircraft was and is the 747-400, which were and are deployed on Pacific routes. IAD will never be able to pass ORD as the largest hub...maybe in trans-Atlantic departures, but if anything, DEN looks like it will be the first to surpass ORD.