Tesla is already there. I mean, Apple could still try, but they're not likely to come up with anything that people will consider "revolutionary".
Touch-screen steering wheel? What could possibly go wrong?
As an aside, I find the obsession with touchscreen interfaces in cars to be irritating because obviously the testers test these things whilst sat perfectly still in a stationary vehicle or in a car with hydrogas suspension (just kidding), and not on a typical road that has bumps. They're impossible to use whilst in motion as your arm bounces around.
Oh yes there is. The car.
Very high margin. Plenty of opportunity to do something radically different.