Do you really think that BMW is going to move away from what got them here? There is a current E92, the F32 will be an evolution of that, just as the F22 will be an evolution of the E82. BMW isn't going to build a Cayman to replace the E92. Compare the F30 to the E90 to see what's going to happen. It will get longer, a little softer and probably a little bit lighter and more efficient.
No 3er has ever been a sports car, this one isn't going to change that. It's not like BMW isn't building a 3er coupe right now, one that still wins awards and comparisons. If you want a "single man" car, there are all sorts of choices out there, German and otherwise.