Shacknews reports that Blizzard has chosen to release the much anticipated Starcraft 2 as a trilogy of separate games with each release focusing on one of the 3 factions. The first game in the trilogy will consist of the Terran campaign, and will be called "Terrans: Wings of Liberty." The second campaign will focus on the Zerg and will be called "Zerg: Heart of the Swarm," The third campaign will be focused on the Protoss and will be called "Protoss: Legacy of the Void."
Blizzard’s Rob Pardo stated, "The second and third games will be like expansion packs, but we really want them to feel like standalone products." He also justified the decision mentioning it was necessary to maintain the quality of the product, the alternatives either being a long delay of the game, or a scaling back of the campaigns.
According to the Shacknews article, each of the campaigns will have different play styles with the Zerg campaign implementing RPG elements, the Protoss campaign will implement diplomacy elements, and the Terran campaign will implement a Protoss mini-campaign.
The very important multiplayer component will be unchanged despite the separation of the campaigns. Some units will be specific to the each campaign and will not be available in multiplayer.
It remains to be seen if the separation of the campaigns is a necessary sacrifice to provide the best possible gaming experience to the customer. Each game will now feature more in-game cinematics and story content. Whether the decision was an unnecessary cash grab or not will become clear after the game is released.
quote: I hope Blizzard puts more "content" into the games before they are release rather than spread the already thin content over 3 releases and charges you for each one.