The RS5 is a great car, no doubt, but it is clear it is not better than the M3. The looks may attract some buyers but the price will keep others away too. I have to admit, if it was materially better than the M3 performance wise, I might have been a little envious given how stunning the car looks. I love the current M3 not just because it was an amazing car when it was released but because it is still the best option in its class 3, 4 maybe 5 years later!! That is an amazing accomplishment for BMW.
If the next M3 is the car it "should" be and materially better than the E9X, it will continue the reign for many years. For all of BMW's warts, it always seems to get the M3 right.