Honestly, considering that LEGO hasn't provided minifig packs for more popular themes in recent years (other than town of course), I just don't see them producing a minifig pack for a theme that has been discontinued for over five years. Fans have been clamoring for more minifig packs for years, yet nothing has been done. Heck, I think there probably is a market for minifig collecting, but I don't think that LEGO agrees.
The thing is, more popular themes have gone without minifig packs for years. The pirate theme has its loyal fans, but it is hardly a major theme when compared to the likes of castle, space or town. And in recent years, only LEGO town has been blessed with a minifig pack of any kind. As an earlier poster mentioned, I believe that this is LEGO's way of enticing customers into buying larger sets. Unfortunately, I don't think you'll be seeing any new Imperial Guards any time soon.
Heck, I've been holding out for a new castle-themed minifig pack for years. That will never happen either. Its just one of those things...
Later.