If they iron out balance to where the top players are very happy with it, address as many other issues and complaints that players had before they dropped the game as possible, and then added the Soviets in?Soviet Union yeeeeeeessssss (or daaaaaaaaaaaa)
The spike in players that the Soviet fans would bring in, plus how such a DLC always caused major spikes in Wargame, you might revitalize the community enough that it doesn't stay so depressingly low.