Greekdude,
From my understanding US Airways was blackmailing Pittsburgh because it was too expensive to operate in the current market. In the contrary, Charlotte and Philadelphia are much cheaper to sustain. Also the O&D traffic is not there so it would be turned mostly into a regional jet operation?

From the troubles at Pittsburgh plus competition from a few other large airline operations in the area (UA at Washington and US at Philadelphia), I was assuming that Philadelphia would probably be one of the beneficiaries of US joining Star? As US would not like to feed connecting passengers off through another hub as competition to Philadelphia, the major US hub with a few other star operations like LH and AC also, I was thinking that an area like Pittsburgh could be shut down. As a hub and turned to regional jets?