I guess it would be necessary to not only bring out call to arms decks for dwarves and goblins but also boost their regular armies.
Currently the basegame has
3x blue dwarf infantery, 1x red dwarf infantery, 1x green dwarf crossbow unit
4x blue goblin infantery, 1x red goblin infantery, 1x green goblin infantery, 2x green goblin riders
in order to keep the specialist card system up, there would be an expansion necessary where they not only include deployment decks but also more of the above mentioned units. Surely with the existing goblin and dwarf units it would be possible to bring out deployment decks, but they would be limited. Plus if you would play against a human army which exists only of normal units you would get quite an advantage if both (the human and the "race" army) get to choose specialist cards.