I think it would be closer to use the fact that During Tiber Septims reign there were No dragons and link it more to the Dragon souls truthfully.
Maybe make it a Transitional thing of after a certain ammount of things they gain a feature.
The overhaul of the main quest would be more the dialogue of how people talk to you due to the features.
I do like the sound of making a transitional change but I wasnt thinking of overhauling the MQ though.
I was thinking of going so far as even changing the feet to digitigrade rather than plantigrade, like dragons and werewolves feet. Id probably prefer to put a restriction on boots like in morrowind and its beast races. i'd also think about putting a few minor reptilian features in, like small scales down the bridge of the nose, perhaps smaller horns for women and larger one for men.
Still cant think of a name for it.
EDIT; After checking out the dragon language, I wondered if Dovahkiir would work.