I doubt they're going to stick around DC long enough to find out if Oleg left Philip a follow-up message. Their cover has been completely blown (or would be as soon as the Bureau nabbed Father Andrei). Any shelter and assistance they might have gotten from the Center is also blown, so they've got to get out of the area and vanish as quickly as they can and then figure out their next steps. Gorbachev's fate, the summit, the Center, Oleg... all irrelevant to them now.