Except for the time that the lenses are bricked while Sigma creates the updated firmware.
You should apply to Canon as an independent fud agent :-)
I understand the necessity of pro shooting are different than for the rest of us, but 3rd party items don't just brick by looking at them, but only after camera fw updates. But *esp* as a pro you don't just update your fw on first day of the release and just before a shooting. You will evaluate what the changes are, and if necessary wait some, for example until 3rd party vendors updating their fw.
Yeah, because people love losing functionality of their gear... not so much. In my industry it takes months to release new software because of safety and certification issues. Consumer electronics is different but it will still take time to reverse engineer and test the changes. And it doesn't have to come with a fw update; it could come with a new camera release. Of course, they never list incompatibility with extant 3rd party gear as features of a new camera.