Take what you pay for insurance. Divide it by 10. Multiply it by the number of FSD cars Tesla has sold.
Now multiply it by 10 for the inevitable negligence claims because they are a corporation and their engineering process will be under scrutiny.
Insurance is just part of the cost of doing business. It's passed on to the customers. Everything you buy has built into its price the insurance the company pays. Taking your numbers (which I don't actually agree with) the cost of insurance per car stays the same as now. But instead of each person paying for their own, the car company pays and passes the cost on to us when we buy the car. Bottom line: No difference.
But that does not kick in until the cars reach level 3, where the car actually takes responsibility. At level 2 the driver is fully responsible. We've had basic autopilot for five years and it's still Level 2 and a beta feature. "Feature Complete" is at least a year away, and I'm guessing three. After that there's at least another five years at level 2. That's at least 8 years before Tesla is willing to say its cars are responsible for decision-making, and we see any change in the way cars are insured.