Well judging by the fact it was first announced on TV Tokyo and hasn't been announced anywhere else yet, you would assume TV Tokyo would be making the announcement. But it could be announced anywhere, I guess.
I don't think we should worry about the January 8th announcement being a spin off game. They probably would have revealed it at Jump Festa if so, and they wouldn't make a big deal about a spin off game by putting a pending announcement message on TV. I think the announcement would more likely be a Wii U Pokemon RPG rather than a spin off (though I don't think it would be a Wii U game either). If its game related, Im sure its involving the mainline games. By the time Gen VI is released it may be over 2 and 1/2 years since the 3DS was out, which is completely unacceptable IMO.
I don't think we should worry about the January 8th announcement being a spin off game. They probably would have revealed it at Jump Festa if so, and they wouldn't make a big deal about a spin off game by putting a pending announcement message on TV. I think the announcement would more likely be a Wii U Pokemon RPG rather than a spin off (though I don't think it would be a Wii U game either). If its game related, Im sure its involving the mainline games. By the time Gen VI is released it may be over 2 and 1/2 years since the 3DS was out, which is completely unacceptable IMO.