Waymo has promised to launch In London and Tokyo next year. New York, London, Tokyo probably covers the entire spectrum of difficulty for self driving cars, maybe we need to include Mumbai as the final boss but I would be happy saying self driving is solved if the above 3 cities have a working 24/7 self driving fleet

The final boss could be something like Scottland mountain roads, or some of the million beaches on a cliff in Greece where this "you have to first reverse" kinda situation happens every 30 seconds.