doing a third box might be tricky sales wise, since it takes sales away from the two dedicated boxes. (and i suspect the male only box will be the most popular anyway, given the general mindset of a lot of minis gamer's i've met.)
i'd say your best bet would be to make it a new product, and market it towards a different style of gamer. the current box basically geared for mass battle games, with its 24 figures. which also puts the price point on the higher end.
but gamers who just want a small unit for games like stargrave, zona alfa, and other skirmish rulesets, often don;t really need a full 24 figures. so why not do a half sized box, with one sprue each of male and female cannon fodder, plus the up[grades sprue to let you customize them more? you could then price it lower (say only $20, or maybe discount the upgrades sprue cost to make it $18). it would sell better to skirmish gamers, and would make for a way for gamers who are curious about Wargames Atlantic's products could check their figures out without having to invest in a full sized box.
you could easily do similar smaller boxes for most of the other factions, especially once they each get additional boxes. Grognards could have 9 infantry (3 half-sprues iirc, with one or more of the head sprues) and one sprue from the command and heavy support box.
and so on.