New supplement will have rules only for stuff all ready released by the time it comes out ( 13.12 ), so it does not rule out possibility for another similar release or bigger supplement later on. Or they will release rules for Dain & Iron hill army on pages of White Dwarf. Or skip them all together, who knows anymore
Small spoiler alert!
I heard that there is huge amount of things cut from theatrical release ( including things we saw on trailers ), maybe they want to wait and see what PJ decides to put back for inevitable Extended edition before producing miniatures for them. Just a guess.