Well, for one thing, I think many people will generally be more aware of Roman history, considering a massive "Roman Successor State" controls Italy, the Balkans, the Mediterranean, and Eastern/Northern Africa. People will definitely be more aware of Italy's existence, and more so of its history due to the fact it'll probably be one of the Great-Powers in the world. The Italian Language may flourish in these areas, so Italian could possibly be the language most people take in school (Considering Italy would probably be an economic power, and with their control of the Suez Canal in the scenario they get their "New Rome", they would be a major economic power).
So, more general knowledge of Italian/Roman history worldwide, and Italian becomes probably as common in Europe and the Americas as Spanish is IOTL.