I hope Zoey becomes a route. Her and Quinn both seem a bit too developed to just become used for side drama. Most of the side girls are well developed but those 2 seem to have a bit too much effort put into them, Zoey being hidden could make sense to be a pretty good twist, but I hope they're not excluded because they'll solely serve as drama or obstacles.
Dpc does a good job of making every route like a connected web, with each route adding things that make you appreciate all the characters more, and I've personally enjoyed all of them. I sadly doubt there'll be stuff like a riona or Nicole route just from the sheer amount of additional writing, but I hope at least Zoey with the interlude and alignment choices gets one. If I remember correctly I think dpc said that the "main girl" or central female character was something that he didn't want to mention at the time, so it'd be interesting if Zoey is kinda the wild card that he planned on being the core love interest with everyone else being equally developed options, and the late introduction to Zoey in Bella's convo could be reflected of tremolo actively trying to not think about her at all from the trauma of only having his dad, being bullied, finding his best friend and lover and then them "abandoning" him, which would be interesting gameplay and story integration.
Worst case scenario though is just her and Quinn solely as drama, Quinn taking coke and od'ing or doing something stupid for a "feels bad man", or Zoey being there so each li has a drama moment and then Zoey and him officially break up, cry, feels bad man, then each li uses that to get stronger and then from then on she is basically female derek. That'd be such a waste regardless of preferred girl, Zoey has the potential to build on tremolos past and himself along with her and Quinn has the potential to explore the "dangerous" dik side, possibly something like having drug dealers or criminals come after her and you have to do a difficult brawler section or else you just get a bad end where they straight up kill you. Maybe a bit too dark but something like that, have a "you idiot why'd you do that" "cause you're my girl" *make out session* that sort of thing.