Whilst that's true, it doesn't seem likely that we go from where we are now (Can't do autonomous driving) to a point where can get fully autonomous driving, and

Whilst that's true, it doesn't seem likely that we go from where we are now (Can't do autonomous driving) to a point where can get fully autonomous driving, and then to a point where we can do fully autonomous driving with the reduced sensors available on existing Teslas in a period of time that makes sense.