I think the main goal of EV's is to be more environmentally friendly. Self driving doesn't contribute to that goal and i don't think it's a thing that will make or break these other manufacturer's efforts.
The trailing manufacturers aren’t building EVs primarily to be environmentally friendly. They are trying to compete for revenue of the growing market.
And also self driving does allow for resource efficiency, which is environmentally friendly. Self driving cars have the potential to drive closer, making better use of limited road surface area and reducing traffic (which reduces emissions of other cars in the same jam). It also allows for fewer cars to serve more passengers.
I think it will be a big factor. Yes, they are two separate things in the car industry. But if I have a choice between two EVs, one with self driving and another with no self driving you bet I'm going to pick the one with self driving. And I'm willing to bet a lot of others will too.
And also self driving does allow for resource efficiency, which is environmentally friendly. Self driving cars have the potential to drive closer, making better use of limited road surface area and reducing traffic (which reduces emissions of other cars in the same jam). It also allows for fewer cars to serve more passengers.