Well, as I said, it depends on the activity of low CN numbers imo. There are around 8,000 CNs available, but I do not think that all CNs will be allocated to the owners of high CNs. On the other hand, late APs might not be able to get their visas on time. I think this cut-off will be in the range of 4,000. The next one will more depend on the response rate.
Actually, this is very unclear, but if they optimized the algorithm of selection and if they actively send emails to the winners in order to ask them to fill the forms, I think the second draw will not be necessary. Although, as I said, it is very unclear what happened and it is too early to make any kind of predictions.