Age of Ice was just the mod/scenario included in BtS. It was a prequel to FfH II.
The Four phases of FfH II are Light, Fire, Shadow, and Ice. The current .30 is the first version of Shadow. The future versions of Shadow should include basically all new mechanics and major additions to the game. Ice will be mostly scenarios, but will also include the fleshing out of the Illian civ. It is suspected that it may include scenarios in which Auric Ulvin (who is possessed by/the mortal reincarnation of Mulcarn, God of Ice) ascends back into godhood and returns creation into another Ice Age.