The correct way is to detect counterfeit parts, display a huge warning and let the customer continue on their own risk. A similar process is used by the Linux kernel developers for non-opensource kernel modules: If you load them, the kernel becomes "tainted" and you won't get any support from the kernel developers if something goes wrong.

Yes, this would be smart.

Probably just putting a message with priority "Error" in the windows event log would be enough to warn computer-literate users.

Yes, people would fault them for removing functionality.

The problem in that case is not the actual new drivers, but the process of uninstalling the old working drivers.