Remember cops are not attorneys. I would never ask a police officer to translate the law for me or take his word for it. Until a law is actually enacted, they usually have no idea about it, as their job is to enforce the laws that are already in the books, not speculate about what might or might not be a law eventually.
I tend to get alarmed when people tell me they asked a police officer what the law is gong to be, when I know that they are trained to get people to incriminate themselves.
I can tell you this with certainty, if the Muniz case is denied by the Supreme Court, no registrants are going to be automatically removed the next day, and the law is not going to be immediately changed. You are likely going to be expected to continue registering while your state legislators work things out.
Keep your guards up until you get official word. I would hate to see anyone get in trouble because they thought it was over.