The Imperial Guard are rumored to be next after Tyranids early 2014, and hopefully with it, a supplement to feed into the Steel Legions. That would get everyones tank armies moving forward.
This rumor today mentions Steel Legions and Mordians as getting some special treatment soon.
Please remember that these are rumors.
via Tim from the Faeit 212 inbox
The Imperial Guard gets both Steel Legion and Mordians in Plastic with the New Codex.