Not sure which part of my post you were addressing but the bolded part doesn't sound like "internal growth" to me. No country can grow in isolation USSR was a prime example of what happens when you try.
Well, a country can grow in isolation, it's just not efficient, due to the laws of absolute advantage and comparative advantage. But, theoretically, one can consider the entire Earth as "one country" and realize that it is growing economically in isolation. The Earth isn't trading with anyone, and it still keeps improving economically.
Unless, once we start trading with aliens we find their economy is built on coal, then we'd be going backwards.
Foreign trade is part of the economy but it's not the tool a country should consider for prosperity . In fact the entire economy of communist nations was geared on exports . The people where being deprived of many products in the name of export . And look what happened to them
Capitalism is the only way to go . But proper laws and proper education are the only ways that capitalism remains a balanced economic system .