What? No that is not how any of this works. There's no sense in which the court sends matters back to congress. They make a ruling that the way an agency has been interpreting a statute is incorrect, and order them to change their interpretation and thus their actions. Congress can of course pass a new statute, but almost always in these modern gridlocked times the real result is that the court's new interpretation is the new law. All that would change with Chevron being overruled is they'd intervene much more frequently based on the easier to reach standard for overrulinig an agency decision.