Even though I believe there is a lot of work to get bad/questionable weather conditions handled, as well as more complex driving situations like 4-way stops, roundabouts, crazy pedestrians, map databases that don't match reality, how agressive a driverless car should be or not in various scenarios to keep itself and surrounding traffic flowing, etc., I suspect the technology will be ready-to-go before the legislation and liability discussions are completed.
For global companies like Tesla working this, its got to be hard enough to build the tech to then handle multiple countries, languages, laws, signage, etc., let alone just here in the US, perhaps 50 States each with some sort of variation how autonomous vehicles are allowed to operate or not -- so a single car can drive itself from the West to East coast. We'll see. It's certainly interesting times we are a part of.