I'm a but skeptical if this is going to be possible in the future - I'd say it's increasingly unlikely that you'll be able to meaningfully change anything in your car.

For example if you look at where Tesla and co. are going, they are looking to reduce the amount and tickness of wiring harnesses - and they did so by creating a proprietary fieldbus that communicates between proprietary controllers that handle multiple functions, so they can multiplex everything under the sun into a single bus.