They could have sold up to 2000 of them! You can sell that many of anything! Go try to build a Porsche Cayenne on their website....when I got done optioning it the price was $193,000...
also I think there are a lot of people currently driving AMG's and M's who would buy RS's if they were available! My guess is that if they expanded the RS lineup then they could easily take at least at least a 3rd of the hi-po luxury market! Audi just builds better cars (just go look at those pictures on the other thread), and if they bring them they will sell them!