She also has something going against her; how she would work. Would Sakurai know how to properly execute Zoroark's signature? (The Illusion, I mean)
And also the fact that she's not very wanted. Sure, she's expected, but if you ask someone whether they wanted her or not, you're most likely going to hear "no" since people fear that Lucario would be replaced by her.
Well, other than Holder's ideas (which were good), if Illusion was a special move perhaps it could give Zoroark the ability to mimic some of the character's A moves as well as appearance, sort of like a reverse Kirby. Sure, it wouldn't cause as many mind games, as opponents could see Zoroark use Illusion and change, but it would still remain fairly faithful to the ability. Plus even if we can't come up with a good use for Illusion, I doubt Sakurai would be unable to.
Secondly, I don't get where this lack of popularity people claim Zoroark has. She appears on most popularity polls (that include 5th gen), and is higher than Victini on a good deal of them. She might not be that popular here, but we are just a tiny sample size.
If Lucario were to be replaced, it wouldn't be because of Zoroark specifically. Any fifth gen rep could hypothetically replace Lucario, as a fifth-gen newcomer will most likely be given priority over Lucario. People who think that Zoroark would replace Lucario due to similar body structure are thinking irrationally, he would be replaced due to lack of time, given the fifth-gen will most likely be added first, if the Pokemon Company has anything to say about it. It could very well be Victini or Meloetta that "replaces" Lucario, it wouldn't only happen because of Zoroark. It's the same as people who think Lucario specifically replaced Mewtwo. Mewtwo was cut because of time constraints and would've been replaced by any Pokemon, it's just coincidence they have a few similar moves and similar body structure.
Lastly, the issue was why she wasn't included as a "maybe". Even if she is just expected and not actually desired, that still means she is expected. If she is expected, then that obviously means she would be a "maybe", whether people believe it is warranted or not. I think that most of us can agree that if 5th gen gets repped, Zoroark is one of the most likely choices (at least top 3).
Sorry the reply took a while, my sunnavabich computer randomly shut down while I was typing it out. Had to retype everything.