There is a lot of historical data on it already. Also in markets much more similar to modern markets, but it’s important to keep in mind that things are different depending on the period.
Today the most valuable parts of a country isn’t raw materials or factories, but know-how, and know-how is a lot more mobile than any other resource.
Romans faced a different threat, in that their biggest resource was the materials and the factories, and because of that, they didn’t want one region to have access to all of it. So they made their weapons in a different place than their food source.
I don’t think protectionism or nationalism has ever really worked though. You mention the Roman Empire, but it thrived the most when it was the most inclusive, tolerating every region and culture as long as they all paid their taxes on time and accepted everyone else. One of the key reasons the Roman Empire originally was so tough on Christianity and Judaism was because the monotheisms didn’t accept others.
I think it’ll be alright though, America has been through worse than Trump and the alt-right.