If this becomes a thing, very quickly you'll quickly see insurance products created for those manufacturers to derisk themselves. And if the self-driving cars are very unlikely to cause accidents - or more accurately, if the number of times they get succesfully sued for accidents is low - it will be only a small part of the cost of a car.
The competitive advantage is too big for them to just not offer it when a competitor will, especially when the cat's out of the bag when it comes to development of such features. Look at how much money Tesla made from the fantasy that if you buy their car, in a few years it would entirely drive itself. There's clearly demand.