IF a certain period of historical gaming (according to the Great Wargaming Survey that'd be WW2 of course) should prove to be overwhelmingly stuffing up the Historicals section you could consider splitting historicals into WW2 and Other Periods. Same goes for the Other Games - Sci-Fi/Fantasy section. Infinity has always been there and rather popular with some but on GW-centric forums it never seems to really break through a certain threshold number of people who like to chat about it on forums.
This makes a lot of sense. It would be easier manage than subforums for every game until interest was properly gauged.