The thing about the design in the Story Mode illustration that worries me is that I could see it being assembled from CaS parts. His head spikes look like those of the generic lizardman, which is based off of his SoulCalibur IV design, but without the frills or fins. His spined armor also looks like it could come from his SCIV design, seen clearly in his art
here.
Honestly, I love the optimism, but I'm expecting little more than SCIV lizardman with the SCIV armor, without the frills and with Sophitia's moveset. The sword looking bigger in the art could just be a perspective thing, or just an art thing, 'cause I'm not even expecting him to be left-handed if he appears in-game.
He has no story potential. He wanders around and growls at people. We have one of those already with Voldo. We don't need two.
Nonsense, he's got plenty of story potential. His plot has parallels to both Siegfried's and Sophitia's. He's a Greek warrior sent on a holy quest to destroy the cursed sword Soul Edge. However, he was driven mad by the evil seed and then transformed into the first lizardman by the cult, which is where he becomes similar to Siegfried. Both lose their minds and become servants of the cursed sword, doing unspeakable things in its name. The main difference here is that Siegfried was kind of a dick when he got influenced by Soul Edge (running with a gang of bandits and killing his own father), and Aeon was fairly heroic (on a holy quest, and planning to repay a village for their hospitality by teaching them swordplay), and when both were freed from the sword's curse, Siegfried got to go back to being a normal human being--with baggage--while Aeon was stuck as a lizardman--with baggage. From there, Siegfried gets to go on a big mopey redemption arc, while Aeon gets abandoned by his god.
The problem is the writers never gave him a means by which he could interact with the other characters, be it broken speech or writing or sign language or whatever. Then they gave up on his plot after III and just kept writing in new plot devices that kept him at goober badguy status. I think he could have had a cool relationship with Siegfried and the Greek sisters if the writers actually put effort into his plot. He and Cassandra essentially both hate Hephaestus and would probably agree on a lot if they communicated, but they pretty much never come into contact with one another. He'd be decent proof to Sophitia that maybe Hephaestus really isn't worth serving.
The Rock business also never went anywhere, but that was a pretty bland plot for both parties to begin with. Talim has had a unique line or two in the games, recognizing that Aeon is human under all the scales and whatnot, but that interaction too was never expanded upon.
Anyway, I'm not exactly expecting much better from the writers in this second go-around even if the game does include Aeon, but the potential is definitely there. It's on the writers for constantly failing to utilize it.