Speaking at Gamescom, THQ boss-man Danny Bilson said that the third Dawn of War will be released roughly 18-24 months after the upcoming Dawn of War II expansion; Retribution.
Once Retribution ships, the team will begin working on Dawn of War III, which suggests that Retribution will be the last Dawn of War II expansion pack.
18-24 months after February 2011 puts a Dawn of War III release at somewhere between August 2012 and February 2013.
THQ has also suggested that depending on how successful the free to play Company of Heroes Online is, they may do the same thing with Dawn of War II. “It may be a more digital free-to-play experience with all the depth and quality of a Relic RTS.”