the average age of a car in the Uk is 7.5 years, and based on last years record of 2.5 million new cars registered it will still take more than 12 years to replace all the cars on the UK roads, even assuming everyone can afford to trade up enough to get a self driving one in that period.
Absolutely. I think I cited similar stats for the US when someone posted a link to an article by some pollyanna futurist. If starting tomorrow the only car you could get was a self-driving electric car, it might take 20 years until they were ubiquitous until we got to a point where you could prohibit human drivers from main roads.
But my training is as a historian of the sixteenth century, so I see that as a fast cultural change. Much faster (though much less important) than the transition to the wheeled plow ;-)
Still, there are technological changes that affect society in ways that we do not expect in advance. Two of my favorite examples are reliable matches and refrigerators. When matches became widely available, this had a profound impact on village life for women in Europe. Before matches, "going to fetch fire" was a common reason for women to socialize with their neighbors. Women became substantially more isolated once matches became available. At the same time, destructive fires become less common as women were not running back and forth among thatch-roof houses with hot coals.
Refrigerators had a similar effect (Lawrence Wylie, Village in Vaucluse documents this for the south of France). Basically, prior to the fridge, perishables had to be acquired daily, sometimes twice daily, which meant people were out and about walking around and seeing each other. Older French friends confirm that when they were kids they went to the market or farmer 2x per day.
We expect that cars and televisions had huge disruptive effects on social life, but it's not obvious when looking at the history of technology to think of the disruptive effects of matches or even the effects on daily social life resulting from home refrigerators.
I expect that self-driving cars, which will have a profound social impact, but it's not clear what all the impacts will be and at what level of penetration.