Simple scenario. How could the Spanish peninsula remain, more or less, under Muslim control to the present day?
And, keeping in mind butterflies (preventing any real parallels after, say, a century or two), how would a surviving Al-Andalus, either unified under a single state (an heir to the Caliphate of Cordoba) or as taifas, develop? Could it remain culturally advanced, relative to the rest of the world, to a similar degree throughout history? How would governmental institutions develop?