Are you still flipping out about the dude using the Spanish western coast as a geographical expression rather than the Portuguese western coast? Its been a week dude. let it go.
But historically there were lots of greek factions and despite units might be siilar ,their political realities were in some cases extremely different and varied.
Same could be said about any faction really. But my guess would be a eastern DLC (Including the much-anticipated and ranted about Selucids) and eventually a steppe DLC or something with Dacia, Thrace and Scythia once they get around to developing some unique campaign functions to depict their semi-nomadic lifestyle.