Bare in mind this is a concept, in my opinion, the rear end (bumper/diffuser/exhaust arrangement) will be changed for something a lot more conventional. My reasoning?
I present to you the rear end of the 6 series 'concept':
And how the production car looks:
It hardly takes a huge leap of faith to expect them to rationalise the rear of the 3er just as they did on the 6er....