I don’t have a lot of information about this, but the Golden Nugget is launching a new 24Karat Club players club. If you already have a card, you will need to get a new one beginning June 17th, 2014.
It looks like cashback is going away, and will be turned into free slot play as of June 17, 2014. Every 100 points that you earn is worth $1.00 in free slot play. A minimum of 100 points is needed for redemption.
Additional details are scarce, but you can see the announcement here.