Indeed, and replace the tribes that were wiped out with loyal troops and people from the other factors of the Empire.
How sustainable would this Empire be? There will be Emperors who aren't as good as their predecessors or successors.
By the modern day I can see modern day Pakistan, India and Bangladesh making up the Indian state.
i can see the eventual civil war in future, toppling of this dynasty and rise of a new one, its survival depends on two things, shared identity, and ideology and language, because if you can convince the population that they got better benefits if they remain within mother nation then empire is sustainable, most of the colonial empire was situated in different continents thus they were much harder to rule also colonies like that only served to extract resources for their owners, so if you can enforce an ideology that will survive beyond any kind of dynasty, i can see eventual rise of democracy because no matter how enlighted no autocrats wants to surrender absolute power.
so we will see a clash of interest, maybe it will turn into a constitutional monarchy.
"We are told to remember the idea, not the man, because a man can fail. He can be caught. He can be killed and forgotten. But four hundred years later an idea can still change the world. I've witnessed firsthand the power of ideas. I've seen people kill in the name of them; and die defending them."