Two routes that I think are plausable..

RDU-DEN (previously served by UA)
RDU-SFO (proposed during the UA/US engagement)

Honestly, with the CO execs in charge, I would suspect that any airport that had service to all the hubs before will have service to all the hubs now..

So I would gather that any airport that saw service to EWR/CLE/IAH.. will probably see service to EWR/CLE/IAH/IAD/DEN.. SFO is my only questionable one.. but I could see UAL doing it..