I have a thought experiment for you. What would it take to have the Roman Empire (or Republic) make a comeback? What bare minimums would recreate a recognizable Roman Empire? Here are a few I brainstormed:
1. Must contain city of Rome
2. Latin official language of government
3. Roman Senate active
4. Army using Roman terms. Legion = division, Cohort = battalion, century = company. Dux = 3-star general, etc
Further questions:
1. Would there be an official religion? I don’t think there would have to be. Maybe nominally Catholic in the west. Tolerance for all faiths would probably be the law.
2. Who would be considered a citizen? Everyone?
3. Would slavery exist? It’s hard to imagine Rome without it but the point of this experiment, after all, is a modern Rome.