Major Update:
Last week, during a Pokemon commercial, a new announcement on the Pokemon series was teased for Jan 8. But today the official Pokemon site itself has updated, formally confirming that there will be an important announcement on Jan 8 2013 in Japan. It tells fans to bookmark the page to prepare for the update next week.
NA Twitter more hype
Original
At the end of a Pokémon Black 2 & White 2 trailer being aired in Japan, a teaser cropped up, being shared around the internet through Twitter, at the end and has stated that the next big news regarding Pokémon will be revealed on January 8th 2013. It's currently unknown what this news is, whether it's related to current games, such as a new WiFi event or if it's a new game reveal. We'll be sure to post the new information, whatever it is, as soon as it is revealed
Also...
Gamefreak director Junichi Masuda revealed on his Twitter in December that he had just filmed an
episode of Pokemon Smash, and since the episodes are recorded a month or so in advance, it’s likely the episode he taped will air in January. Masuda usually appears on Pokemon Smash to make game announcements.
Pokemon 6th gen 2013, believe.
I hope it is a new game!