I just spotted a brand new published Olympus patent. It describes a 12-35mm f/1.8-2.4 (24-70mm f/4.0-5.6 FF equivalent) MFT lens. The main characteristic of that lens is that it is collapsible. The patent mentions that this lens can be used for both fixed lens and system camera versions.
It will have pretty much the size of the current 9-18mm lens.