If anyone else has noticed, it is infact, springtime, a time in which many mainstream games for Pokemon are announced. this, to my knowledge, includes Diamond/Pearl, Platinum, Heartgold/Soulsilver, and Black/White, all announced in the Spring, and eventually all came out that same year in the fall (for japan) and then around a year later for the US.
With this pattern, there is a great probability that a mainstream game will be announced, though one thing that could get in the way of this is the fact that a new generation was just released, meaning a mainstream game won't be announced for another year (next spring, 2012). If a mainstream game is not to be announced, one could speculate that a spinoff game could be in the works, of which could be a possible sequel to Pokemon XD Gale of Darkness, as it is technically a mainstream game (an RPG, with a storyline, catchable Pokemon, trade them to the main-mainstream games)
EDIT: Lets not forget that Colosseum came out almost exactly a year after Ruby and Sapphire, so a sequel to them (Colosseum and XD) could come out this fall (2011) and be on store shelves roughly a year after Black and White.
With this pattern, there is a great probability that a mainstream game will be announced, though one thing that could get in the way of this is the fact that a new generation was just released, meaning a mainstream game won't be announced for another year (next spring, 2012). If a mainstream game is not to be announced, one could speculate that a spinoff game could be in the works, of which could be a possible sequel to Pokemon XD Gale of Darkness, as it is technically a mainstream game (an RPG, with a storyline, catchable Pokemon, trade them to the main-mainstream games)
EDIT: Lets not forget that Colosseum came out almost exactly a year after Ruby and Sapphire, so a sequel to them (Colosseum and XD) could come out this fall (2011) and be on store shelves roughly a year after Black and White.