My guess is that the Feb. 11 announcement will not be anything quiet as dramatic, more likely to be something like an announcement that Iran will push ahead to produce 20% enriched uranium using its own means instead of trying to reach a deal through the IAEA to exhange it for LEU.
Iran will not use a dirty bomb—if they do the west will respond with clean nukes and lots of them. Most of what is said it all talk but, such things could become a cause for war. The nation of Iran is falling apart from the inside and they may seek a war to unify their people. Wars have a way of taking on a life of their own. What you wanted to do at the start isn’t always they way things turn out.