TaaS will get a fast start in cities and then radiate outwards to suburban and rural areas. As adoption increases, a tipping point in availability will be reached early, when it becomes feasible for car owners to rely entirely on TaaS. As used cars supply increases and demand decreases, values will plummet. Those steadfastly sticking to individual ownership will be far more likely to buy used cars, driving down new car purchases dramatically and leading to a death spiral of reversing economies of scale, increasing costs and leading to supply chain breakdown. Over time another tipping point is reached where gas stations begin to close down, spare parts disappear and maintenance becomes harder or costlier to find. ICE vehicles will become harder and more expensive to use. Consumer opinion moves from being a brake (scared of autonomous vehicles) to being an accelerator (seeing human drivers as reckless, dangerous and slow), driving regulation that bans or restricts human driven vehicles. Barriers perceived to slow adoption of EVs like range or charging availability are not relevant to TaaS trips where cars will have sufficient charge for trips ordered and car relays, battery swapping or fast charging will enable longer trips.
We see no supply, demand or policy constraints, meaning that within 10 years of regulatory approval of TaaS, the vast majority of passenger miles travelled (95%) in the US will be with TaaS. Even in the rural areas, where wait times and cost (due to redundant trips) might be higher, lower incomes will motivate adoption as will the increasing cost and difficulty of using a gasoline vehicle. The only hold-outs might be the very rich, the most rural or the equivalent of those who still use horses for transport.