I think the issue here is that we are really talking about two different things, but attributing the benefits of one to the other. Yes, one needs the other to function, but at the same time the other doesn't necessarily need the first to function.
We have (1) Autonomous vehicles and (2) the move away from vehicle ownership.
AV technology may reduce the cost of renting a vehicle for short periods over a human driver, but it is fundamentally different from the move from vehicle ownership itself.
While AV is likely (and sensibly) going to come to fleets first, it's unlikely to stay that way for very long. Once the technology matures enough to be available in consumer products (lets say around 3-5 years after in some cases) most of the benefits you are currently attributing to ride hailing are no longer exclusive to that.
For example the benefit of not having to drive is there for both the ride hailer and the car owner, benefits such as not requiring to find a parking spot, or not needing to pop out and pick others up will be available to both ride hailers and car owners. Those are discussion points for AV, not ride hailing and car ownership.
Then there are discussion points regarding car ownership:
- The ride hailer doesn't have to store or maintain their vehicle, but have to use it like a taxi now, removing everything they own from it, not knowing what the condition of the car will be like, potentially having to wait for a free vehicle (this will happen, even if you can schedule a vehicle unless there's a significant over supply of vehicles). They also need to deal with issues that may come up if they need to travel longer distance.
- The car owner has to store it (on the road in front of their house, or the drive, or a garage, or a car park somewhere relatively nearby) and maintain it, but don't have to worry about removing all their belongings, or what the condition of the car is like, or whether one will be available. With parking especially, AV reduces that "issue" as the vehicle can drop you off at your front door/destination and head off and park on its own.
- AV does not preclude companies from offering restaurants on wheels (we have food trucks and delivery services already), or cinemas, or VR/AR (why can we have video screens in cars for passengers now, but not AR/VR for example?). The cost of a driver in those circumstances are either already included (the food trucks and delivery) or would be relatively negligible relative to the cost of the vehicle and the profit it may be able to make (what vehicle do you need for a mobile restaurant or cinema, an HGV at least? A Mobile restaurant would likely need a chef and waiter at the very least anyway).
These are all unrelated to AV technology. Ride hailing is available now, you can rent a car for a long weekend trip away now (and many do).
The only real thing that ties these two factors (AV and ride hailing/car ownership) is cost. If the cost of ride hailing falls low enough that it negates the negatives people have with not owning their own car then people will transition. That cost/benefit ratio will vary significantly from person to person. For example, even if we halved the cost of ride hailing with AV I probably still wouldn't use it. It would still be cheaper to take the train for my commute, and I would still value the benefit of my own car to pick up shopping, or do other errands, over hailing potentially multiple vehicles for the same situation. I don't think I'm alone in that sentiment. That's now, when the choice is to drive, or get someone else to drive for you. In the future when I wouldn't have to drive either way (both owned and hailed vehicles being AV) then one of the current major benefits of hailing is not there any more.
All that said I don't think AV ride hailing is a bad thing. It will almost certainly be beneficial and make a significant profit for the companies involved. There's already a large market served by taxis and ride hailing which will likely transition over to AV services, just as other driving jobs will (hauling etc). That market will probably increase a bit, as mentioned before perhaps by removing the need for a second vehicle in some families, but there's no reason AV alone will change the face of car ownership. What will is societal changes, which are largely unrelated to AV now.