Absolutely brilliant mate! One thing though... The flag on your Swedish units is actually the Danish flag (pre 1219). The black raven banner (like the one in my avatar) was called Dánibrokí (the cloth of the Danes) and was a black
I don't mind the "what if" approach, those American Hoplites floating around are pretty cool.
Now we have:
Ancient: Zerver's ancient americans(I think it was Zerver)
Medieval: Your new American units
Renaiissance: Colonial Americas
etc
American hoplites eh? Where are they?
I also made Renaissance and Industrial Americans too buddy.
As for the flag. I am using a "Native-American" stylized Eagle for their ancient and classical flag. For their units I use Native American looking units but with a red, white, and blue color-scheme. For their Renaissance-era I use the revolutionary-era 13 stars in a circle, then I use a field of stars for their Industrial and Modern eras.