Considering Viktor's story, I fear for Syndra, LeBlanc, Kassadin.
And pretty much every other champion who has an evil motif going on but with grey morality.
Syndra is the "dark" sovereign, so I wouldn't be surprised if she was changed from a girl driven by immense anger, fuelling powerful magic would suddenly be changed into some girl who's trained all her life to be strong at magic and uses it to destroy Ionians for no reason other than REVENGE!!!
I mean, that's pretty much her story right now, but the nuance is that her motivation is because she was continuously put down and mistrusted with her power, and after shaking off the yoke of oppression Syndra has become the voice of the downtrod and oppressed. She represents potential. I'd hate to see that story twisted into "Syndra would've been evil no matter what happened because she is an evil bi-- woman."
The same goes for LeBlanc (black rose?) who may be retconned into being evil for the sake of being evil, and Kassadin, who looks and sounds like an evil dude but is totally a defender of the innocent... If he suddenly becomes Overlord of the Void, I would not be surprised at this rate.
Some of this is hyperbolic. However, I would like to express that even if Riot's lore team insists on going forward with this new direction where Viktor isn't understandable and sympathetic, but just an evil jackass who kicks puppies because he can, that they avoid similar writing in the future because it is not compelling and, honestly, off-putting from what had been a great character.
(added by 2016)'s quotes for
According to this,Kassadin is Anti-Void champ. so he is NOT evil.
even if they change Kass's lore,he is still preserver.i just hope they will describe Kass&Malz's relationship particulary like Viktor&Jayce when they will add Void lore.