Of course not, but having the tech tied to an electric push I think makes the whole package more attractive to consumers. Perhaps I'm too tied to a Tesla mindset on this though, of course self driving cars offer a bunch of advantages on their own.
I have a strong sense that self driving will be generally distributed through the US car population before electric only vehicles given the pace of software vs. pace of battery technology. This will drive mass adoption of gas powered self driving cars pushing back the adoption curve for all electrics. One way to stem this may be through tax and insurance incentives, a discount on self driving due to safety, a discount for electric for environmental reasons, and an extra discount for both.
I was under the impression that electric cars had a lower cost per mile, but the electrics have a higher up front cost.
If you have a self driving fleet (eg. Lyft, Uber, GM, etc.), you'd want to optimize for the former, not the latter. Uber has proved that if you can get a car within a couple of minutes at a low enough price, it's a valid enough substitute to car ownership, at least in cities.
