I think the confusion on the "launch" being in the Vert is the following. The first media images, advertisements and movies about M-DCT were all showcasing it in the Vert. It was just a way for BMW to announce the production of the tranny previously described in the long technical document describing it. It also makes sense to talk about the two together becuase there is a match of sorts between the DCT and the Vert. In general those with a less true motorsport type of interest in the M3, and those more concerned with looks over performance will be drawn to the Vert. Similarly the interest in an "automatic" will probably be higher among those serious about the Vert. Again not making any blanket statements nor conclusions about any one future owner, just observing some likely trends.
Since the Coupe and Sedan will be released slightly before the Vert and based on how far along many members cars are in the production process there is simply no way we will see Verts with DCT in the US before Coupes. BMW has just chosen an interesting definition of "launch".