You are Correct. The Demon box comes with the car right off the showroom so it’s considered stock. The PCM upgrade is covered by the factory warranty. The GT500 will never run 9’s bone stock. The Demon will hold its value much better than the GT500.
The 2020 GT500 may be the last all Gas big HP mustang that Ford produces. The exotics are all going Hybrid/Electric of some kind in the next few years. In 10 years it’s doubtful they will still be selling all gas high performance vehicles. So your Prediction is correct!
The ZL1 is a performance bargain and a better platform than the Mustang. You can also buy a ZL1 at a discount the new GT500 will have a epic ADM. they need to release more info on the GT500 soon.