I'm very much looking forward to self driving cars to save us. It's hard for public transit to cover enough of a city, but we can easily build trunk lines or commuter lines and have self driving cars carry people the last mile. Public transit could then focus its limited dollars on rail for the most heavily trafficked corridors. No more slow and infrequent public buses. This would also encourage density around stations, while allowing those who want their back yards to live further out.
Traffic (along those trunk routes). Cost (some say Uber's price would drop by 2/3 with self driving, but for a long commute, a $3 train ticket is probably still cheaper). Self driving cars would be great though if your route is not a standard suburb to downtown route.
