The Supremacy Clause applies to the states. That’s why it is supreme. States may not enact laws that are in conflict with a Supreme Court decision. So, in response to your question, if the outcome is positive for the registered citizens of Michigan, it will be a positive outcome for the registered citizens of every other state because those states cannot maintain registration schemes which continue to impose ANY restrictions that the Court disallows. However, we are really way ahead of ourselves since we have no way of knowing how the Court will decide Snyder if it grants the petition. The decision is just as likely to be negative as it is positive.