Well MQB based Audis (A3 and bellow) have a technically different awd system than MLB Audis (A4 and above), which is different still from the system employed in R8. Yet from a marketing perspective, all of them are called quattro. So if future large Audis adopt the new Porsche MSB architecture, past has indicated they can use the their awd system as well and still call it quattro. Most of the customers won't know the difference anyway. On the other hand MSB might be flexible enough to allow for different implementations of AWD. In that case Audi might choose to adopt/develop their own version, different from Porsche.