Gilda is such a fun character design. On top of that, I actually really like her character... Admittedly, it's one that can't be a regular in a show as positive as Friendship is Magic, but I have a fondness for jerks who can cause conflict and make biting comments, as it only tends to endear the sweet characters they pick on to me more. Plus it's always fun seeing the jerk get put in their place. And unlike, say, Diamond Tiara who seems to go out of her way to be pointlessly cruel, Gilda was just really, really, really ill-tempered.
If Trixie can make a comeback, it seems only fair that Gilda show up again in Season 4... maybe competing in the Equestria Games?