Wild speculation, based on the fact that we haven't seen her in a long time: I wonder if there's any connection between Evelyn and Vigilante. Her desire for vengeance against Oliver would suggest that she wouldn't stay quiet on the sidelines for this long. Has there been any scene, so far, that would exonerate her from actually BEING Vigilante? (Such as, she was with the team while they fought Vig, or something similar.) Although, as I recall, she's pretty short, compared to the rest of Team Arrow, which would suggest that she isn't.