No doubt there already have been dissertations written on this topic, but it's very rare to find thriving, big-time college football programs in major urban centers, including Philadelphia. This, of course, is chiefly the result of local or nearby NFL franchises' garnering fan support that might otherwise have gone to a college team. In particular, potential "sidewalk" fans are channeled instead toward NFL teams because the affinitive price of admission is merely that one identify himself with a certain city. (I'll admit my biased view that getting excited about the NFL is generally for people who didn't go to college.)
If Notre Dame had been established in Chicago rather than South Bend, would the Irish have any more football cachet than the Northwestern Wildcats? I doubt it.