I've talked with too many people that would buy the game if there were dwarf or orc.
With that said why couldn't this game have 8-12 factions. Look at WHFB. Sure the FotM armies that just got updates had a lot of play, but that didn't stop people from playing factions that didn't get updates for years. Say that early 2018 gives each of the 4 races 2-3 new unit options. Then late 2018 could be spent on fleshing out new factions. I wouldn't see an issue going 1-2 years without another Daqan expansion.