Here's one interpretation of what the M3 coupe's successor may look like.
Production of the current E92 M3 Coupe will end in the middle of next year, and its successor is expected in 2014 boasting a model name change. Similar to Audi's A4 sedan and A5 coupe, BMW will differentiate the coupe and sedan by giving the former the M4 moniker, while the latter will retain the title of M3. Given the M3 coupe came before the sedan, you would have thought the high-performance 4-door would have adopted the new name; you'll have to ask BMW for their reasons.
These renderings, via automotive artist Iacoski, demonstrate one interpretation of the 2014 M4 coupe, based largely on spy shots of the new 4-series coupe but with some added 'M' styling. Sporting the popular shade of alpine white, the renderings are nicely perceived although we'd expect BMW to manage something a bit slicker.