What happens if you disconnect the antenna? I recognize that they could be made integral to some other components, but at least in phones where I've removed radios and cameras, that has never been the case.
Do the cars have some sort of spite-brick functionality built in if the cars can't phone home? This is purely curiosity; I doubt that I would ever buy a GM car.
Currently there's a dedicated fuse for the OnStar system. You can pull that and the consumer facing OnStar functionality stops working (remote monitoring, etc). I assume it's really actually fully disabled by the fuse, but I can't guarantee it.
Do the cars have some sort of spite-brick functionality built in if the cars can't phone home? This is purely curiosity; I doubt that I would ever buy a GM car.