I think you will find pretty universal legal and political agreement that a decision by the Supremes is and has been interpreted for at least since the middle of the 19th century as superceding any extant laws which run counter to such decision. Look at Brown vs Bd of Edu and Loving vs VA. It took years for the states to change their laws to comply with the courts ruling (some probably still have not been removed from the books) but desegregation and inter-racial marriage went forward immediately despite southern efforts to block the changes. I wish your theory was true so that any state that desired could ignore Citizens United which put a "for Sale" sign on the Congress and White House.
If we ever reach the point that we as a people decide we can ignore the decisions of the law courts we have renounced the rule of law and might as well tear up the Constitution.
As for the mayors of "sanctuary cities", if it can be shown that any action they took was counter to their oath of office to uphold the law, then they should resign or be impeached. The problem is, producing that solid evidence is a lot more difficult nut to crack than the nut in KY.