I'm in the same boat as you. No new sensor hardware from the outside of the car, reversed stalks without ACC label, and 5.14. I suspect that we could do the hardware upgrade. Wouldn't be surprised if the wiring is already there for us and the sensors are not. But beyond the sensors I suspect the car needs at least the following additional parts swapped:
* Windshield (to have the right cutouts for the camera)
* Rear-view mirror assembly (for the camera and whatever is behind the slits)
* Headliner (to accommodate the new rear-view mirror assembly)
We know the windshield is about $1200. I doubt the rear-view mirror is super expensive. The headliner change is probably not terribly inexpensive. No idea on the sensor costs. I kinda doubt the steering wheel has all the feedback bits in it (though maybe it supports it). So I'd bet on something like $5k to retrofit it to one of these inbetween cars, assuming it has the wiring. If it lacks the wiring the costs grow dramatically from there. Not only do you need to have the wiring and the sensors but you need to have something to plug it into. Which means almost certainly upgraded boards for the computer system. I'm assuming if you have the wiring you have the computer system changes.
If it's possible to retrofit to my car without being terribly cost prohibitive then I'll probably do it since not having this is somewhat eating at me. I'm not even the slightest bit bothered if they announce an AWD S because I don't have any reason to need an AWD car. But lacking these sensors probably means missing out on a ton of features that I suspect upcoming software updates will add.