We sold the Prius and started being a one-car Tesla family in January 2013. Sometimes it made things difficult with two schedules, but mostly it has worked fine. We have never worried about being stuck with a Tesla needing parts, etc.
Then in January of this year our car was involved in a parking incident where someone in a pickup cut in too quickly to a space in front of the car and ripped the nose off. Freaky, for sure. Being Saturday, it was a little difficult getting a rental, but our local body shop towed the car into their yard.
Firstly, there is no such thing as a "Tesla approved body shop" in CA. Any shop must be approved by any manufacturer. And secondly, Tesla parts are a problem. The first week, my body shop told me they couldn't get parts, and I read posts here about people waiting months to get things from Tesla.
I got on the phone and wrote emails as soon as I heard about it. I soon was talking to a Tesla regional parts person and being assured I would get my parts "tomorrow". They did pretty good: It took a week. My car was fixed within 30 days, and insurance covered my rental.
Yes, renting a car can be a hassle. But any part of any accident is a hassle. Nobody wants to have this kind of fun, but here you are, no choice.
So, I have lived for over 3 years with only one car. I survived a month long repair by driving a rental. I don't think the chances are long that anything like this will happen again for a while, and I have not paid for registration, insurance, fuel, depreciation, etc., that goes with a second car. It worked well for me.