Ah but what will that effect be? There's nothing about a self-driving car that increases road capacities. And since a self-driving car doesn't get bored or frustrated, there's less of a disincentive for a self-driving car to drive during rush hour. So it seems like if all else remains equal, self-driving cars are going to make traffic worse, not better (sure, if you could combine them with ride-sharing, they might reduce things but lyft and Uber right now could be ride-sharing but they aren't. No reason to expect a self-driving taxi would better unless something impels it).
Now, if these self driving cars were high passenger capacity, that might have a great effect- but of course then we'd just call them a bus.
This alone might make it appealing to take normal methods (car or autonomous car) into the city for leisure.