My prediction is that Zoey is being brought back as a IL, just to offer DIK MCs another option. I come to to this idea, because right now, we have Jill's story that links back to the MC's mother somehow, and if he follows that, it'll lead back into that more and more.If the DIK/Neutral/CHIK system is a moral one, being DIK bad and CHIK nice, it means that DPC is taking part for a route, and if he´s coherent, the DIK MC is going get the worst ending, and the CHIK MC is going to get the best one. It would make the game less interesting, IMO. I find the CHIK route boring and less interesting in general. Not because I´m an asshole in real life, answering the question you make in your comment, but because there are less things to do in the CHIK route and the situations and characters are less interesting. DIK MC is more bold and assertive with girls, and able to standing up against assholes that bully him, like the Alphas, and I like that in a character of a H-game. I would not like to be punished by DPC for that at the ending of the game.
But, there's an alternative: the MC's own history. It doesn't involve his mom and dad's life together. It doesn't involve how the rich families might relate to each other. What could be important is the MC's personal history with the surfer girl.
You know, Jill could have had more involvement with DIK MCs by playing with her memories of Lana (the rebel dead sister). She could perhaps see similarities between her sister and the DIK MC, and depart from her rich upbringing to tell a story similar to the one his mom had with Neil. But, I'm pretty sure that's not on the books. At all. DrPC could have done that, but he didn't, and it's too late to do that now. There's a certain story waiting for Jill and the CHICK MC, and as you're probably aware, it's a very boring one.
When I was doing my playthroughs with CHICK/DIK/NEUT, I wasn't even really reading the CHICK stories. I mean, I did, but it didn't make much difference, since I'm not really relating to those girls at all, now that most have rejected the DIK MC.
The coming S3 does provide a chance to reset the table though. I wouldn't mind if there's a more DIK-focused apprach with the overarching story. That would be a pretty great balance to the game. I'm not sure if there's a demand for that, but it couldn't hurt.