I, too, would love to see the ability to play a Goblin or Human tower/town (Elves aren't popular enough to warrant it and would probably have to wait until the magic system allowing them to create/shape wood for their dwellings is worked out, while Kobolds would need to have the game allow for their inability to dig into hard rock, which, in Kobold Camp, is currently achieved via making them the only playable race and setting most rocks to the hardcoded value of [IMPACT_FRACTURE:5000000]), but I suspect it will have to wait until later versions, as doing so would likely require many adjustments to simultaneously suit play with these three civilizations.
In any case, I'd like to see expansions of the Humans first, in a Black-and-White sort of direction (a god game where numerous tribes existed on the same lands, from Japanese to Aztec to Celtic to Norse to Greek and so forth). Things like analogues to Mesoamerican cultures (Obsidian swords, complex systems of agriculture, caste systems, blood, massive constructions, the capacity for exotic animals and bizarre religions are already in game, so why not?), North African tribes (would add a rival for control of the savannah lands with the desert peoples, not to mention a fearsome stock of war elephants), Middle Eastern kingdoms (to sit on the opposite biome as the Nords), Indian sultanates (to fill out those rainforests and jungles, and provide a potent agricultural superpower to rival the Wesmans), Polynesian island peoples (though that may have to wait until trade boats are implemented) and Slavic steppe-peoples (a mountainous civilization would provide a human competitor to dwarves in that biome, and a Tibet analogue would be too similar to the Osmans for my tastes, and a faction of hard-living, nomadic horse archers would be a thing to contend with.)