Could the Italo-Normans become even more successful than they were in OTL? The Hautevilles were undeniably incredibly successful, but what if they were much more organized and centralized? Could the Italo-Normans build up a strong centralized core to ensure their longevity?
Perhaps a good idea could be for the Komnenids to never rise to the throne and the Normans taking Byzantium wholesale, with all it's centralization and the bureaucracy that supported it. The Normans would still quickly take on the religion and culture of the Byzantines, but it would still count as an Italo-Norman state for a few generations.