Extending the Patco to 30th street would be nice. In fact, extending the Patco to 30th st would just be like extending the Path from the former World trade center to GCT.
Interestingly enough, extending the PATCO line to 30th St. was very strongly endorsed back around 1975 in a DVRPC "50-year plan" master proposal. At the time the Cardington branch was pretty well intact and the old P&W connection was salvageable, so the plan included the possibility of further extending both lines to connect in West Philly. Since the P&W and PATCO share many operating characteristics(*) the idea of joint service was not so far-fetched as it might sound.
Of course we're now 30 years into that 50-year span, the Cardington branch is essentially inaccessible, and SEPTA (if it survives) is unlikely to tolerate any increased competition from PATCO on what it considers to be its own turf.
(*)IIRC when PATCO was planned, its designers studied the P&W as a model of the best way to run a "pre-metro"-style rail line.
