Frankish Empire?

I am always at a loss when I read about historic leaders with enough foresight to keep their Empires running and growing, yet they do not see far enough into the future to ensure what will happen to it when they are no longer around. Although Louis the Pious was able to further Charlemagne’s, his father, accomplishments he did not see that dividing up the Frankish empire would lead to it’s demise. I feel grateful that even though the system we have in place for our leaders leaves room for improvement, we also have a way to get rid of the “Louis the Fats” and “Charles the Simples”. We are also very fortunate that we have separation of church and state. Can you imagine with the diversity of religions we now have, how much worse our battles might be. I wonder if the main focus was more on gaining land and power, more of an ownership, rather than building an empire to ensure its continuance for the people. Would the Frankish empire have persevered longer?