I think besides all the problems they all have in their hands right now another big problem is slowing down for curves without changed speed limits. There are several curves I have taken on freeways and felt very uncomfortable with autopilot and especially on local roads this makes a huge problem. I don't know how they would determine how much to slow down based on the angle and distance of the curve. Another obstacle to find a solution for.
Here is my wild ass guess but I hope it's true. Tesla stated FSDC which is Level 5 autonomy.
Experts seem to think you need Lidar for that. What could be better than Lidar is real time mapping via camera and distributed information sharing. Think waze. With half a million cars on the road, Tesla could conceivably record every possible driving surface in the world.
The first car through that curve it's gonna be ugly but the cameras figure out the curvature of the road and the next car handles it better, etc?
I hope this is possible.