reginos:
The day will come soon when we will see a Porsche based on the Audi RS3 or the Audi RS6 because such models are potential best sellers and more profitable too, since they could be sold at higher prices because of the Porsche badge.

Yes, Porsche US sales for March were down by 5%, whilst Audi sales were up by 18% for the same period. If this trend keeps up, expect the above to happen sooner rather than later.