I reckon it's extremely likely to happen, it mightn't happen straight away with with the facelift model but I bet it will come at the time that the F30 M3 gets launched.
There's fundamentally nothing wrong with the sum of the parts that make up the RS5, in fact I would go as far as to say it's technically the most advanced in this category with the best engine, best gearbox and best chassis, the only thing missing is lightness, the car is crying out to go on a diet. If Audi could help it lose 100-120kg this could be a quite remarkable car to drive.