While the statement suggests the studio is still sorting out the game's future, as far as Eurogamer understands, Relic has no plans for additional content. This means no new expansions and no additional races will be added to the game in the future.
For more on Dawn of War III, be sure to check out IGN's review of the RTS/MOBA hybrid.
In addition to an unannounced project, Relic is currently at work on Age of Empires IV, which was announced last year at Gamescom. Brian Barnett is an IGN freelance writer. You can follow and chat with him (he's super friendly) on Twitter @Ribnax.