I wonder what they would do if another state were to set state law specifying the same, or better still one week before Iowa. Would they both just keep moving t

I wonder what they would do if another state were to set state law specifying the same, or better still one week before Iowa. Would they both just keep moving their primary/caucuses back until it is set immediate after the inauguration of the last election or would the supreme court tell then both to knock it off and set the dates for everyone.