I doubt autonomous car makers will offer this themselves. They'll either partner with existing insurers or try to build a separate insurance provider of their own which does this.
My guess, if this actually plays out, is that existing insurers will create a special autonomy product that will modify rates to reflect differences in risk from standard driving, and autonomy subscriptions will offer those in a bundle.
Bundling a real product with a financial institution is a time tested strategy.
Airlines with their credit cards are basically banks that happen to fly planes. Starbucks' mobile app is a bank that happens to sell coffee. Auto companies have long had financing arms; if anything, providing insurance on top of a lease is the natural extension of that.
My guess, if this actually plays out, is that existing insurers will create a special autonomy product that will modify rates to reflect differences in risk from standard driving, and autonomy subscriptions will offer those in a bundle.