Some of the effects will depend on details of the implementation. For example, if self-driving cars are constrained to obey highway speed limits, the commute time may increase in some cases, at least initially. Upon achieving saturation of self-driving cars, I would expect shorter commute times on non-highways. Also, upon saturation, it may be seen as desirable to raise the highway speed limit.
Keep in mind that non-self-driving cars will always be cheaper and will always have a market no matter how good autonomous ones get since autonomous vehicles have more parts and maintenance needs. You will never have an area with only autonomous vehicles, absent massive government intervention.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
Duration set to six days to encourage Monday as first day.