Dont think it will be US airways.
They downgraded LGW to a B752 as part of the move to LHR, and in turn LHR has been downgraded from an A333 to a B762 due to lower than expected loads.
On top of that, the new daily service to BHX has been downgraded to 5Xweekly, and now MAN has the only UK-PHL A333 this year.
So, seems like US are struggling to fill planes as it is, so doubt that they would want to bring a new station online bearing that in mind.