I love this idea.
I think it would be cool to not know it is your champion, he's just the default at first. Then after playing the multiplayer, maybe you go back to the single player campaign for a while. And what do you know, there's the champion you've been building since then.
You didn't even realize that's who it was at first. Nice little perk to replaying the game again.
I doubt theyll have time to do it. Im pretty sure the whole game is already completed. They just need to constantly play the game now to find any bugs so they can polish it so its perfect for release. Maybe what they can do is add kratos to favor of the gods sitting on a thrown how hercules is in the beta. And when u win he jumps down to congratulate u kind of thing.
But good idea though