There are three big hardware hurdles I see Tesla facing: the lack of side visibility at long range, the view distance of the low res cameras, and the current road infrastructure not supporting autonomous driving in any way.
The lack of side visibility really worries me, currently it seems mostly the job of the forward facing wide angle lens, perhaps supported by B pillar cameras that seem really aimed down for road line viewing.
Currently, the camera footage looks like it has the quality of a ten year old webcam. There is no way it can compete in clarity with the vision of someone with 20/20 vision. When I'm driving I'm identifying hazards such as police speed traps, debris on the road, potholes, erratic drivers, etc from a long distance, sometimes up to a kilometer or more. I believe autopilot has a stated range of about a quarter that, 250 meters. At only 120kmph (around 75mph), you cover 33 meters a second. Only about 7.5 seconds to identify and react to a problem (assuming the problem isn't coming head on at the same speed, in which case, halve that). The radar can help in a forwards facing issue, but for monitoring blind spots, it isn't so useful.
Finally, and this is a big one, our roads and driving system as a whole are around the idea of human drivers. Stoplights could have something like infared flashers to send signals to autonomous cars, but they don't and probably won't for decades. Similar tech is used in my city to allow emergency vehicles to communicate with a light ahead to make all 4 directions red and stop traffic. It's not new or revolutionary, but it is expensive to add in and considering no cars use it right now, it would be a waste. Heck, forget that fancy tech, in many parts of Canada they can't even keep lines painted most of the year because of snow.
Another thing to consider, almost everyone in society is okay with 40,000 deaths or so in America because of driving accidents. Now look what happens when autopilot has a single accident with the driver misusing it. International news. This mindset will also take decades to overcome and allow common sense legislation regarding level 5 autonomy.
To sum it up, I don't expect robotaxi's in 2020