I think the Glorious Duce might have had greater ambitions than those of real life. Rather than being content with control over the Italian peninsula and the colonies in East Africa, I think he may have attempted to expand the Kingdom, perhaps starting with Dalmatia south of Istria, then moving on to Crete and Cyprus, and perhaps even attacking Istanbul in hopes of unifying the nation as a third Rome. Whether these territorial ambitions would have sullied his reputation remain to be unknown.
I don't know if Rosa Luxembourg and the communists would have been able to gain any influence at all in Germany. If the rest of the world were just as bellicose as before Kellogg Briand, perhaps the Reich would have militarized. Maybe they would have attempted to reconquer Alsace-Lorraine. I don't know what else the Germans really would have a legitimate claim to, however, so I doubt the Germans would be able to do much.
Whether or not the African colonies would still be under the control of the Europeans is unknown. If war had not been abandoned, I doubt the peaceful liberation of Africa beginning with Italian Somaliland in 1942 would have been possible.
I do wonder, however, if it would have been better for the blacks in South Africa. While the whites did grant them limited representation in the parliament, perhaps a brutal war would have permitted blacks to gain more power in South Africa. While they are far from second class citizens now, I wonder if they could have earned even more rights than they did in our time.
Any thoughts?