Interesting thesis. Sicily, and most of the other examples that I can think of that would fall into this pattern, had been subjected to centuries of foreign occupation. Focus on the family, broadly or narrowly defined, was probably a necessary mechanism for physical and economic survival in that situation. Clearly unhelpful going forward, though. Has any work been done on societies that have shifted from amoral familism to something else?

A minor point: Banfield's study found amoral familism not in Sicily but in mainland southern Italy. Banfield states that Montegrano is in the province of Potenza, which is part of the Basilicata region of Italy (Moral Basis of Backward Society, pp. 1-2). Basilicata is known as the instep of Italy.
The book is worth rereading every few years. I'm glad to see it included here.

Has there been similar research on Chinese culture? It might also qualify as an amoral familistic culture, but without sufficient knowledge and expertise I cannot say for sure.