I'm hearing reports this week from the final wave of diversity visa interviews for the 2016 lottery cycle (shared in a Farsi-language Telegram group and translated by my wife) that conoffs at posts that issue visas to Iranians (at least Abu Dhabi and Ankara) are telling all applicants as they come to their interviews to try to reach US soil and establish residency immediately due to the risk of a sudden overruling of the preliminary injunction on EO 13780.
My personal read of 13780 was that all visas granted during an injunction period should in theory remain valid even if the injunction is withdrawn or the order itself is found valid in court, though I suspect that they are probably right to give such advice given the unpredictability with which CBP has been acting in recent months. I would hope that we would have at least a week or two of warning that a Supreme Court ruling may be imminent seeing as the courts have thus far not bought into the Administration's argument that there is an truly time-sensitive national security imperative to enact the "ban," but I could be wrong.