[SEFTA]

Driverless cars will play a part. Not the only part, and I hope not the biggest part. I believe it will be a combination of many and depending on your driving needs. There is a reason transit hubs are making come backs. Demand. Congestion and parking is simply making it more reasonable to take other means.
If you're running errands around the Walmart-land, your driverless car is the way to go. Headed to CC. You'd probably want to take the train. City dwellers shouldn't have to rely on a single form of transportation. That is the advantage of living in the city. Philly has a strong rail infrastructure. It only makes sense to build on that.