I doubt that car insurance is dominated by fixed costs - istr payout rates are over 70%. Even if the number of policy holders falls by half (which is unlikely to happen in a decade) premiums shouldn't skyrocket.
More robot cars on the road likely make it safer for the remaining humans, which will tend to lower premiums.
The only problem is if the most dangerous humans prefer to drive themselves. I can see factors in both directions.
More robot cars on the road likely make it safer for the remaining humans, which will tend to lower premiums.
The only problem is if the most dangerous humans prefer to drive themselves. I can see factors in both directions.