Okay so for a fair time we know that Malzahar took Kassadin's daughter into the Void and Kassadin went after Malzahar. Why isn't Riot excelling the story further, like that Kassadin's daughter (Could possibly) become a new champion.
This is one of those dangling plot threads that may or may not ever actually be resolved. Right now Kassadin's daughter is sitting with Irelia's Brother, Kog'Maw's daddy, Jinx's Sister, The Ruined King, Professor Stanwick Pididly, Marcus DuCouteau, and countless other sorta mentioned characters in the abyss that is "Waiting to be made a champ."
It is escapable. Sejuania and Lissandra did it. But for now they are background characters.
Riot centers new lore mainly on new champs,but they usually don't design champs with the thought "hmm lets turn X who gets mentioned in Ys lore into a champ" but more along the lines "man lets think about what would make an awesome champ".
So as far as i understand it champion design comes first and if said champion design matches with a character who was mentioned in the story before,then he/she could take that place.
