Well it sounds like you agree that it would decrease over that time at least some though just that you don't think it will be some revolutionary thing.

That's totally valid. It will take a good amount of time even just for regulations to allow it. But it is very expensive to have a car in a big city and IF the robotaxis would be able to get to you anywhere in a reasonable amount of time I know that from just cost alone that many in cities would forgo owning their own car. But that is because you can walk most places already so you don't need them as often. If we are talking about suburbs I could agree with you as I have no clue how that would look.

I do think they will need to have something like renting a car though for like long trips and such which would make what we are talking about easier to handle for the general public.

Now stay with me in this hypothetical land of things that could happen. If self driving cars become a thing in the next year or two that no decrease in private car ownership would happen in the following 13-18 YEARS. I'm not saying full self driving will happen that soon but this is the hypothetical situation we are talking about. You don't think that it would at least cause some decrease in private car ownership? like in large cities?

Price. It's that simple. If what Elon is saying is true and it will be cheaper than a ticket for the bus I'd have a hard time arguing not using it. Also an Uber comes with the expectation of a human being in the car and for some that makes them feel uncomfortable