The other possible future is you rent the car for exactly when you need it and don’t pay a monthly bill— or your monthly bill pays for a certain number of rides/minutes/miles per month. In which case the subscription costs are managed by the provider, who might be the manufacturer and might not.
At least in cities, a fully-functioning, on-demand autonomous fleet would probably be superior to car ownership in just about every way except as a status symbol.
The monopolist providing this service would be de-incentivized from ever equipping for all the demand, and the last 10% of capacity being bid on by the last 20% of demand would make this a constant stress and struggle.
Meanwhile it's an excuse for another century of more car lanes and less mass transit infrastructure.
There used to be a service like this, called Car2Go. Not autonomous, but more like how scooter/bike rentals work. It was fantastic, and in no way profitable.
At least in cities, a fully-functioning, on-demand autonomous fleet would probably be superior to car ownership in just about every way except as a status symbol.