Over the years, I have been truly unimpressed with the knowledge of dealerships. It's too bad BMW doesn't give them more accurate information.
As your surmise, we don't know...but most of us still hope that at least the next generation M3/4 will have a MT option. Beyond that, I agree we're beating a dead horse. At that point, used BMWs or Porsche it is!
Or...for my DD I just may give in a buy an electric car. For some reason, the lack of a MT seems less of an issue to me in an electric car; it's just a different experience.