I remember in a Fox Chat from awhile back, Peter Staddon said that he would have to check if they had the rights to release it, and if they did, it would definately be released. I don't think we ever got an answer.
I don't see why not. It's already available through Columbia House as one of their "TV Greats" subscription series, so there's no reason to think that Fox won't give us a retail release.
I don't see how Fox wouldn't have the rights to it. Whomever has the rights has obviously licenced it to Columbia House, anyway. Maybe Fox is waiting for their "exclusive" deal with Columbia House to expire. Certainly, other shows that started out as club exclusives (M*A*S*H, Sanford and Son, Soap, Wonder Woman, etc.) have been released in seasons sets at retail.
Actually, Columbia House no longer offers Alien Nation the Series. They did release the entire series, but none of the follow-on movies. At least one of the films has appeared on Fox Movie Classics in recent months, so I think the films are clearly in the Fox library.