As they are monthly contracts the expiry will have very little impact. Traders that want to keep their positions open will simply roll them over into the next month's expiry. I really can't see much reason for anyone to actually use the cash settlement option. The only scenario where that would happen is if there was a large price discrepancy between the futures and cash markets prices, then there would be an arbitrage opportunity. Even in that scenario, the volumes on the futures are so low it wouldn't have much impact on the cash markets.