Actors from the '91 series attended several '90s Fests - but if I understand the thinking correctly (and this has come from some of the '91 series' stars themselves), they believe there's no interest in having them attend as fans are seemingly only interested in the original stars. I can't say I agree with that because I would love to see actors from the '91 series attend. But there you have it. And if there's a belief that there's no interest in having the '91 series' stars attend, well, it's pretty much a certainty that the same belief is held with regard to the '04 pilot's stars.
As for Kathy Cody, I believe she was supposed to attend a past Fest but never showed. It would be great if she does indeed show up this time. But if history has taught us anything when it comes to the Fests, it's always best to consider the inclusion of some actors' names as hoped for appearances (and "special" announcements as hoped for announcements) rather than as certainties...