Re: Current Manufactures...
I'd assume it is not the tech side of things but the branding. The tech is doable by anyone with the skill set, though might need retooling (see designing a fluid clutch for a sports car https://youtu.be/glf_k4qGBAA the exiting industry cannot do it due to momentum, but newcomers can).
However the sales are down to marketing and consumer opinion. When you have 100s of years of branding this is where it is at. Here in the UK (why did I bother posting anon?) we have seen countless century or older brand bought out only for the label. Millions of consumers still buy the brand, but nothing except the colour of the sticker on the box is the same, yet they dare not "change brand" for fear it will "be lesser quality". Little do they know, both come out the same factory!
Same for the self driving cars, the winners will be those who get the marketing, tech and production right, but not necessarily those who have those things now.