Need I remind you that the original Pen F had a reflex viewfinder 50 years ago and wasn't any bigger than the digital PENs?If you add a VF to the pen format, then it won't look like a pen anymore. To big a part to insert in the body to keep the same look.
Or that the E-330 also has a reflex viewfinder and has no "hump"?
I'm confident in Oly's engineering prowess and their ability to design a solution that can keep the size down.