Once people realize that the self-driving dream won't be taking place anytime in the foreseeable future, I'd expect another big drop.
i'd say the next 5-10 or even 20 years certainly falls under the 'forseeable future'
If you look at VR, which I think is simple in comparison, you could have experienced it in a high end 90s arcade. It is only now starting to become a mass produced product.
In my view, the current self driving cars look like where VR was before they turned the technology into arcade machines.