The followup to Pokemon Black and White isn’t the predicted “Gray,” it’s Black 2 and White 2, coming to DS in June. There’s not much information about them yet, except that they’re coming out, and there are two new legendary Pokemon for the covers.
They’ve also been announced for North America, as “Pokemon Black Version 2” and “Pokemon White Version 2” which sounds way less sequel-like. Ironically, “sequels to existing games” would be one of the most innovative things ever to happen to the franchise.
It also represents a step forward for developer Game Freak: the ability to use the same license to sell four games instead of just three.