After the E extension is finished, at current levels WN and FL should both be able to co-occupy it. FL has 4 gates and only needs 2 of them so the city is likely trying to get them out of D. Also WN will eventually move out of its 4 gates in D to consolidate in E.

DL/NW need to figure something out with regards to gate space in PHL. Neither occupies enough gates to handle the full DL/NW operation. DL 3 or 4 in A and NW 3 in E with ~40 flights a day.

I doubt CO is going to lose a gate in PHL, unless they start to use UA gates during some of the non peak times.