This could definitely open some floodgates. Sonic Team is showing four titles at Space World (For those that don’t know, Space World is Nintendo’s Japanese showcase of upcoming games). We know of three, which are Phantasy Star Online (GameCube), Sonic Advance, and Puyo Puyo, both for the Gameboy Advance. However, there also seems to be a mystery fourth title lurking in the shadows from the team… noone outside Sonic Team knows what it is yet, so it could be any number of things…
Source: SwirlVision