Little thing i put together using the latest photo shown of the 4 series, Scott's sketch showing us the tail light design and this f30 3 series photographed by John Zhang. Should be enough to give you a rough idea of what this car will look like. Enjoy.
All credit given to LTBMW & 1013 Photography by John Zhang and BIMMERPOST for original spy photo.
Based off this spy photo:
And these previous sketches by BMW insider Scott26: