First, find the problem
I can see three separate types of failure that could lead to an event requiring liability to be identified
1.) An operational failure (including a mechanical problem)
2.) An implementation failure
3.) A failure to define a suitable standard of operation
Operational failures, such as a blow-out, computer failure, faulty battery have a lot of case history to determine where blame lies. There would obviously be some extensions to this as new technology becomes included, but that is always the case.
An implementation failure is an entirely new concept. Since having a software driven vehicle (i.e. fully autonomous - no human input at all) is something that has never been considered. This is what the new laws are all about. Every level of "autonomy" lower than this - the ones that require a qualified driver to be able to take control - is already covered.
But a failure of the vehicle's (and we are talking lorries, buses as well as cars) systems does need to be defined. And the liability has to be determined.
From the point of view of either someone inside the vehicle (aka a passenger) there can clearly be no blame. Thus everything else comes down to "equipment failure" - just who's equipment would merely be a matter for the various suppliers to sort out in civil proceedings. But that is no different from what we have today. I reckon the major legal cases would be between the (vehicle's) insurance company and the producer of the vehicle - and after that between the maker and their subcontractors.
The third point, about situations that aren't covered by the safety standards imposed by governments is again, something we already have to deal with. Those will get closed as a matter of course, though probably only after the fact, as accidents happen and regulations get tightened.
From the cyclists' point of view, I would get worried. All these (truly) autonomous vehicles will have such a vast array of sensors that they will record every facet of an accident. Video from every direction, audio, weather conditions, positions of every object in the vicinity. All of that will be of "forensic" quality, It wold be very difficult for a cyclist, or pedestrian, who was faced with a weight of evidence that they were in the wrong, to defend against. No longer would there be an automatic presumption that every collision was always the car's fault.