I agree with your conclusion, but I think your analysis is dead wrong. I don't think Apple would have problems manufacturing cars at scale. They have virtually unlimited money to aquire people with the know how, and to invest in factories. And they have lots of experience with manufacturing already. Sure, cars are different from consumer electronics, but not in any insurmountable way.

The real reason I think Apple would pull the plug on it's car project, is if they believe we are about to move to a transportation as a service world. Ride sharing and self driving cars are trends that point in that direction. Apple is a (consumer) product company. Their internal structure is set up to make the best consumer products and sell them directly to consumers. They are not set up to be a services company. Being a (successful) services company is to some extent antithetical to being a successful product company. Apple knows this.