Aftermarket head units are needed for this to work. Bundling it with a new Ferrari aint going to be a big earner.
I'd love an aftermarket screen--not a new head unit, though, just a sturdy dash-mount touchscreen to add to my "pre-iOS-in-the" car that lacks any touchscreen. (Or even to a car that has a touchscreen, but not an iOS-ready one.)
It could communicate to the car's built-in stereo/mic, and receive steering-wheel controls, via Bluetooth. The car would see this unit just the same as an iPhone, and integration with the existing stereo need not change at all from the way iPhones already connect. (Which works pretty well.) The car doesn't need to know!
But the aftermarket screen would, in turn, connect to the iPhone via Bluetooth. The phone would connect to the unit, not directly to the car. A "man in the middle" offering a bigger touchscreen and a driver-centric UI.
Since iOS-in-the-car isn't meant to control random car stuff like temperature (thank goodness--give me knobs!) I don't see why this wouldn't be practical. And way cheaper than some manufacturer option, and reaching a much larger audience: existing cars and any make/model that has BT.
I hope someone steps up to fill that need! Seems likely.