" When they buy a new PC they will not have a choice."
Sure they will.
1 reformat and install the Linux distro of their choice. Or, if they're up to additional work, BSD,
2 buy a Mac in the first place. Apple doesn't give a damn what OS you run. Install a Linux distro, install BSD, even install Windows, Apple doesn't care. They won't support you if you don't have an Apple OS running, but they don't care what you have running. They'll even provide Windows and (some) Linux drivers for you. Then you're on your own.