Since DFW is a larger hub than CLT, there is every reason to believe that DFW will become the primary east-west hub along the southern tier of the US. It is also true that CLT's island service will become less necessary - at least at the same levels - as what AA carries thru MIA. OTOH, PHL is a larger hub than what AA has at JFK and US has little true hub competition. The chances are much higher than any that a combined AA/US will favor PHL over JFK and will be able to grow the operation based on the alliance. PHL is ripe for Latin America growth in a merger as well as a flight or perhaps two to Asia. With TATL gateways at DFW, ORD, CLT, and PHL, AA/US would be overhubbed to Europe. As for the PHL airport, a 2 year lease extension is not a whole lot - but US knows full well that billions of dollars in improvements make the hub unworkable. PHL government officials know the choices for a NE hub for US or AA/US are not great so they can put the screws on US.... the drama won't stop anytime soon.