Analysis from Bulbagarden from Neogaf (Bulbapedia, Pokemon Encyclopedia):

One more point in favour of why this is likely to be an announcement of mainline games....

The Pokémon anime in Japan has already reached the League, and that'll be over soon. We know they're going to follow that up with a story arc based around N (and presumably Team Plasma). While we don't know how long that arc will be, it would seem difficult to draw that out for too long. There's not really a lot left in B2W2 to develop into another story arc, besides maybe the World Tournament, and that's arguably already been done with the anime's "Junior World Cup" anyway. Barring the creation of an anime original region (which they've avoided since the end of Gen I), something totally unexpected (visiting regions from spin-off games like Colosseum), or the anime being brought to a close (highly unlikely), they're going to need a new game region to go to.
http://www.neogaf.com/forum/showpost.php?p=46057650&postcount=494

I'd guess Gen3 remake for 3DS.

I would like next gen, but i also want to hear a wiiu pokemon stadium-like game. For whatever reason, stadium games hype me up to play the portable games.

OMG! OMG! OMG!

Please be a ruby and saphire remake on the 3DS, never played the hoenn games at all.!

I just wanted to come in and throw a heap of fuel on the speculation fires...

Yes, there's a worldwide announcement regarding Pokemon on the 8th of January. But it's not the only gaming-relevant thing happening that day.

8th of January is the day that CES (Consumer Electronics Show) starts. Coincidence? Maybe. But maybe not. What if the big announcement is connected to something at CES?

Hype increasing, but it probably doesn't have to do with Pokemon. You're right though that this seems gaming-relevant since this originated from a Black/White 2 trailer. Can't wait for CES.

What do you mean, "doesn't have to do with Pokemon"? The teaser was on a Black/White 2 trailer, but more importantly, there's now teasers on pokemon.com, and on the pokemon twitter feed. It is definitely about Pokemon, and all but certain to be about a game.

My personal preference is Pokemon Snap U, but I don't think it's actually going to happen, based on what we now know. Generation 6 is the most likely thing to announce, with Pokemon MMO and true 3D Pokemon adventure of Wii U being secondary possibilities (MMO being much less likely than the others).

I was talking about the CES part.

It's tough to decode everything going on with Pokémon right now. The anime is stalling for time with a Team Plasma arc. No upcoming game is currently officially known to be in development. GameFreak says the series will "evolve" in 2013, but will it be a meaningful evolution? IGN noted that "Recent Pokemon announcements [...] came directly from Nintendo rather than through The Pokemon Company itself."

Black and White 2 having come out barely six months ago in Japan, it seems entirely too soon for 6th Gen to be ramping up. It is certain that there are multiple Pokémon games currently in development. If any is to be announced in the next few months, my bets are on a 5th-Gen battle sim (analogous to Stadium, Stadium 2, Battle Revolution, etc.) for Wii U.

The series' Japanese release history supports this theory:
Red & Blue -- 1996
Yellow -- 1998
Stadium -- 1999
Gold & Silver -- 1999
Crystal -- 2000
Stadium 2 -- 2000 (same day as Crystal)
Ruby & Sapphire -- 2002
Colosseum -- 2003
FireRed & LeafGreen -- 2004
Emerald -- 2004
XD -- 2005
Diamond & Pearl -- 2006
Battle Revolution -- 2006
Platinum -- 2008
HearGold & SoulSilver -- 2009
Black & White -- 2010
Black 2 & White 2 -- 2012

If a 5th-gen battle sim is coming, it's coming soon. If 3rd-gen remakes are coming, they're coming soon. And 6th gen will follow soon after both. Either way, given IGN's observation, I don't think January 8 is the day we learn about any of those things -- but if it is one, again, I'm betting on the battle sim.

Guess who's joining the hype? The man himself, Junichi Masuda!

Check! Check! Check! RT @Pokemon: Pokémon fans, mark your calendars! Check Pokemon.com on January 8th for some big news!

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