It can be an announced, unannounced, or a rumored game. It doesn't matter as long as it's reasonable, meaning that an unannounced game would have to be a sequel to an already established franchise or a workable spin-off.
My pick would be StarCraft 2. I don't even know if this game has technically been confirmed yet. There were tons of rumors years ago but lately I've heard squat about it. Come on Blizzard, give us what we want. Don't put out another MMO cash-cow.