I personally don't care that some FWD cars are coming. If they are crap and don't handle I won't buy one. I'd put money on it that 90%+ of models will remain RWD.
I'm sure though the customer base that buys 1 series without knowing about RWD or heritage will plough money at a roadster... All that means is BMW take more of the market and in my mind are more likely to spend some money on some really special things e.g. a new M1