Also, saying that Uber/Lyft need to create their own self-driving cars is ignoring the fact that other companies that create self-driving cars are, and will likely continue to offer rides in their cars through existing ride sharing companies.

That remains to be seen. If a company is able to create self driving cars, what's the value add provided by Uber and Lyft? Having a middleman TNC platform skim some profits doesn't really make sense from that perspective.

Compared to achieving reliable and cost effective autonomy at scale, building a ride sharing app is trivial, and customers have indicated that they're willing to install another app if the fares are cheaper. The complexity of getting a self driving service is high enough that there probably will be only a few entrants in the market, unlike the current value add provided by the TNC apps that match customers with a large pool of individual providers.