I believe the change in national parks says that you may carry a concealed weapon in a national park ONLY IF you are in compliance with state laws. So if you are caught carrying concealed in a national park when you should not be, then they would be enforcing the federal law that says you can't carry unless authorized in the corresponding state. They would not be enforcing the underlying state law. That state law only serves as a basis to decide whether you are violating a federal law or not. At least that's the way I understand this.