I've slowly seen some mainline flights come back to PHL when AA pulls down the schedule in the winter. I checked the last Monday in Feb. and found more mainline in PHL than I remember in previous years. Most notably, and increase in capacity on PHL-AUS/MSY
2/26/18 - Mainline only (minus the 190)
PHL-RDU: 1x 319, 1x 738
PHL-DTW: 2x 319
PHL-STL: 1x 319
PHL-PVD: 1x 319
PHL-PIT: 2x 320, 1x 319
PHL-MSP: 2x 319
PHL-MCI: 1x 319
PHL-AUS: 2x 319
PHL-BDL: 1x 320
PHL-MSY: 2x 319, 1x 320