As above, these skins would be based on what the champion would look like if something had gone a little bit differently in the lore. An example would be Warwick if he had actually managed to slay soraka. Another good skin would be if Shen and Zed were switched in terms of story.
Any thoughts?
I would think it would be cool if in an annie skin when she would use tibbers it would be like a volibear skin on him.
What about Wukong 
if Master Yi 
never taught him?
I approve. Rangar without meeting Kha'zix. Morgana that isn't a fallen angel. Preacended Xerath. all would be cool.
Solar Goddess Diana and Lunar Godess Leona would be pretty cool
Really want to see live Orianna.
This is a great idea, of course the whole "readability/easy to id each champ" thing would come into play, but as long as you don't deviate too much from the base champ idea it should be k.
This is already in place in some champions. For example, the Pre-void Kassadin 
skin.
