Who Owns Tomorrow's Autonomous City Cars?

Jump forward a bunch of years. Cities continue to get bigger and even more people need to get around. Uber/Lyft-like services have evolved and are more efficient and better than ever. Full autonomy has also been realized - there are no human drivers in the city. Autonomous vehicles of all sizes are dashing around and providing awesome, cost-effective, on-demand transportation throughout the city.

Question: who owns all of these autonomous vehicles?

Possibilities:

1. Random people. They “rent” them out to on-demand services when they’re not in use. Seems super unlikely - why bear the cost and hassle of owning a car in the city when such great service exists?
2. The Uber/Lyft companies of the day. Maybe? A very different business model than Uber and Lyft today, and, again, kind of a hassle to own those distributed assets.
3. Car manufacturing companies. Also maybe. Again, pretty radical business model shift from today.
4. Cities. The new model beats mass transit, so they outlaw private vehicles and run the fleet themselves. My bet is some city will do this.
5. Specialized fleet management companies. Similar business models exist today, such as car rental companies, but do they transition?

I’m actually not sure - any thoughts?