What should really happen is that PATCO should terminate at 8th and Market. Then riders could transfer to SEPTA from there. SEPTA could take back the Locust Street Line, and extend it into West Philly, terminating at the Penn Medicine Station, 40th Street portal, or the Airport - some intermodal hub, and not just a random end station the way PATCO terminates now.
It makes sense to have a station at Rittenhouse Square, but it would be odd for that to be a PATCO station instead of SEPTA. Rittenhouse Sq should be accessible primarily to people of Philadelphia, not just people coming in from NJ. Nothing against people from NJ