Avant popularity in the U.S. just doesn't justify high powered wagons for the number of cars Audi sells. Remember, in terms of sales volume, BMW and Merc still outsell Audi in the U.S. by a good amount. That said, there should definitely be more of an RS presence overall. There should be some degree of competition for AMG and BMW M, which have models in virtually every class of car and SUVs.
I would like to see:
RS5 coupe and Sportback
RSQ5 SUV (with the RS5 motor)
This I think would be a good overall position for RS cars. And they should become available at the start of a model line production or no more than one year later, like AMG and M cars.