I can see Lila being used as an excuse to suddenly shift Chloe into being a better character on a more constant basis, since she wouldn't need to be reset to her usual behaviour to create conflict anymore, with Lila around to create conflict in her place.
I could also see Lila taking over as 'Queen Bee' of the school, bossing people around and causing conflicts to get her way like Chloe does, but using her lies so that the students don't see her as a bad person or the one in the wrong like they do with Chloe. Which would obviously conflict with Chloe since she's meant to be the one with all the power at school.
And since Sabrina doesn't have any character of her own outside of her subservience, she could leave Chloe to become Lila's 'best friend' instead, since she's become more powerful than Chloe in the social sense. Which would conflict with Chloe more because Sabrina's meant to be her friend, not some liar's.
And, of course, they would obviously come into conflict over Adrien. Chloe has shifted from being in love with Adrien to being an over-protective friend between seasons, but I can see her saying that Lila isn't worthy enough to be in a relationship with Adrien.