Tanker -
First question - who knows? On the AA side there have been various pushes into MIA on the 767, 320, 737, DFW on the S80, and JFK on the 737 and 320(??). No one knows until after the fact what the last drop was. Shoot, with the demand for bodies in LAX I wouldn't be stunned if we had new hires going into the 320 in LAX.
Second question - from reading posts it appears that PHL is the junior base. Post NIC/SLI resolution everything is subject to change. But history would indicate that PHL probably stays fairly junior.