What about M3 cabrio.
Or even better: rumored M6 CSL.
Tokyo Motorshow is just around the corner.
And mind that 3er sedan (as well as touring) is about to be facelifted very soon - so It's highly unlikely BMW will present M3 sedan before 3er facelift. Eg. Z4 M models & M5 Touring were presented with regular model facelift, same case is expected with M3 sedan.