> Physical buttons and dials for users to interact with that still can be changed by the system are wholly possible.

Sure, but irrational. One of the largest benefits of physical controls is physical feedback, like being about to feel if you've reached the max cold/hot ceilings or the state of the switches.

To make them voice compatible you have to remove that physical association (e.g. infinite spinners, or blind switches), which means now you need to take your eyes off the road to use them, which was major perk of physical controls.

Physical controls that have no physical state are the worst of both worlds. You've lost the physical and electronic control's advantages while adding the disadvantages to both.