Comment by mort96

So this article isn't about a kill switch, just blocking downgrades and custom ROMs.

But to answer your question: we know iPhones have a foolproof kill switch, it's a feature. Just mark your device as lost in Find My and it'll be locked until someone can provide your login details. Assuming it requires logging in to your Apple account (which it does, AFAIK; I don't think logging in to a local account is enough), this is the same as a remote kill switch; Apple could simply make a device enter this locked-down state and then tweak their server systems to deny logins.