I assure you they won't. It's not going to be that expensive to only show an option if you're in California. Companies already do this with other things like privacy related stuff.
If the company is already a scumbag company that makes it impossible to cancel, this will only stop them where they have to follow a law.
What are you referencing specifically? I work in payments and I've never heard of this IBM code. The card networks just use an ISO format and every front end is different (the two we have are completely different in very fundamental ways though they are definitely both old as fuck).