All named characters bar Luke And Vader have been released as blister packs. With Greedo coming next I'd like to see the whole bounty line up within the next year.
We also had C3PO and R2D2 released as a single pack, so there's some precedent for possibly releasing these together.
To elaborate, the base set was followed by IG-88, Twin Shadows was released at the same time as Boba Fett, Return To Hoth came alongside Dengar, and now Bespin Gambit included Bossk as part of its wave. So we have every reason to believe that 4LOM and/or Zuckuss will be released along with whatever the next expansion is, and I'd put money on them both being released at the same time even if they aren't in the same pack, since the two are inseparable in lore.