Why not both? Eventually whatever connection you're using will be dated and considered inefficient crap. Would you want to have to deal with Bluetooth 1.0 today?
Use a standard modular platform so you can hook up whatever SoC you like. Whenever the old one gets dated, upgrade it and get all the latest fancy radios.
A modular platform is a much fatter interface than a display + touch peripheral. To me larger, more complex interface is more likely to go out of date and focused minimal interfaces last longer. People are still using VGA today, and will be using HDMI/DVI for a long long time. Whatever I carry as a phone is going to be updated much more frequently than my car or even a radio/consumer electronics module in my car.
We're in agreement there, I'd prefer a USB link to a proprietary automaker module interface buried in the dash. The bigger problem is to me is that auto makers don't want to make a simple elegant peripheral interface as much as they want to own more of the value in the vehicle - which leads to more complex modules and are likely to put more effort into a more easily outdated interface.
Use a standard modular platform so you can hook up whatever SoC you like. Whenever the old one gets dated, upgrade it and get all the latest fancy radios.