'Muscle Cars And Trucks' is reporting an insider tip that the C8 will have an ECU that is blocked from being re-tuned or modified. They are saying that GM engineers have "super-encrypted" the program so that any attempt to modify it will cause the unit programming to "self-destruct." They expand on this saying that if it finds any coding that is not "as it came from the factory" it wipes the entire unit requiring re-installation of the stock coding.
But you've already thought of three or four ways to get around this haven't you? But wait there's more. Keep in mind that GM recently made an announcement that a completely new electrical system will be in ALL GM cars by 2023. The new digital system, we were told, will include the capability of receiving communications from GM. So GM could periodically trigger a self audit of the ECU as implied by the rumor.
Why would GM go to all the hassle of doing this? Probably Warranty repairs. Folks running an aggressive third-party tune, blow the engine, then restore the original tune then seek a new mill from Chevrolet under warranty will NOT be able to even run the aggressive tune - if this works.
The C6 was the first ECM that was, supposedly, not modifiable but it just took time to crack the code. The same is true for the C7 Z06 codes. But of course, the big difference is the possibility of the GM direct communication with the car.
So for what it's worth that's the rumor