While it wasn't exactly a single player career mode, I remember Sega did have a feature in their old Joe Montana football games where you could play as a single player in a game i.e. as a wide receiver, or as the quarterback etc. I remember hoping that they would expand on this idea but they never did. It is a good feature, and would work well for those of us who like to create themselves and put themselves in franchises(like me
). I wouldn't be surprised if someone eventually implements this feature into their game.