socially and politically powerful minority [e.a.]
Yes, I think clearly the balance of causative processes is likely to be complex in many social systems. In some examples (perhaps including the one you suggest?) a point is reached where the 'net social energy' has transferred out of the dominant elite's hands, and at that stage the language is likely to start to follow new paths. An analogy from the earlier states of English language development might be the Middle Ages: the narrow elite of King and Court spoke French, but the social shifts were creating a new mercantile middle class, and their vigour and increasing power drove the creation of ME, incorporating much French and Latin into the substructure of Old English. Chaucer was the leading exponent of this process. And as in your example, the script took a slower path to change, though change it did.
I guess Arabic script still has one or two vested interest groups keeping it alive... ;)
