I think you hit the nail on the head - Obviously when Tesla have saturated the potential of vision, they should bring in LiDAR if it can be reasonably added from a hardware point of view. Their current arguments make this clear - it would be surface-level thinking to add LiDAR and the kitchen sink now, complicating the system's evolution and axing scalability.

But we're far from plateauing on what can be done with vision - Humans can drive quite well with essentially just sight, so we're far from extinguishing what can be done with it.