Don't many automakers outsource level 2 driving aids these days? Typically someone like Mobileye?
It can follow the traditional OEM outsourcing route, where OEM has high-level models and gets suppliers to implement the details. e.g. I can find public information that Subaru use Veoneer cameras, Xilinx chipsets, but defines their own algorithms. I would speculate they have an outsourced company convert algorithms to FPGA netlists/embedded code. (On the other hand, I know other OEMs have a more complex mesh of joint ventures)
Edit: Re-reading your post, you were talking about the future. You make good points; I will be interested to see how it plays out. Probably as long as the technology remains radar and cameras, it will continue to be easily outsourced.