Can't tell you if they will expand it, but I was flying BWI-SFO tomorrow and was able to change to a cheaper flight out of MDT tonight connecting through IAD, plus got confirmed for first on the IAD-SFO portion. Because of the travel waiver they didn't charge me the $150 change fee and they refunded me the diff in ticket price of $125.
Since the storm isn't supposed to hit until later tonight, hopefully everything will be ok..
First post - great site.