By "outside the city" do you mean the burbs or actual rural locations? Rural locations people will still own cars and trucks at the same rate, but the burbs are where this will explode in popularity. Co-op programs have a problem with reaching into the burbs because of sprawl and lower density which makes getting to a co-op staging area for a car a problem. But putting staging areas a 5 minute drive or less away from customers where autonomous vehicles can congregate until they're called will drastically improve the service's reach. And they don't necessarily need to drive you into town, just to the closest subway, train or LRT station.
Think about it, you're getting ready in the morning, just about to take out the trash to the corner and have your last sip of coffee. You hit the "call" button on the app, the car wakes up and heads to your house while you finish the garbage run and put your coffee cup in the dishwasher. By the time you have your coat and laptop bag sorted, the car is already outside waiting for you. The app on your phone could even have a countdown timer until the car's arrival to allow you to plan every second.