When Persian Empire was restored after 500 years, why Roman Empire shouldn't? But I think it's little impossible in this time. It's not good age for restore any imperium. I read articles that European union is something like modern Roman Empire, but there is lot of differencies. New Roman Empire should be restored from Italy, but in this case Italy should be strong (very strong) european superpower, what is not. Germany has better economy, Britain has better (maybe) army etc. But in future things can be changed.