The US federal government would simply do what it always does in these situations: ignore the referendum, allow it to proceed, and intervene when "votes" turn i

The US federal government would simply do what it always does in these situations: ignore the referendum, allow it to proceed, and intervene when "votes" turn into "actions". (Even then, as with cannabis legalization, sometimes the feds ignore "illegal" state actions as long as they aren't too threatening to federal authority.)