Some of the things I'm about to say are merely speculation, so don't take this too seriously:
Well... announcement teaser, press conference, +16 age restriction "due to the nature of some content".
This means that a new game will most certainly be announced (so WotLK is excluded).
Due to the huge amount of hints, rumors and the events in the last 8 years, it's extremely likely that Diablo III will be announced. Though there is still a very small chance that Starcraft Ghost may be announced (again) and have a Mature rating. Also, although very unlikely, project Hydra might not be Diablo, but a game of a new franchise. Either way, I don't think the new game will be the next-gen MMO, since (if I'm not wrong), Blizzard only started hiring people to their next-gen MMO project last year, meaning that it's probably in an extremely early development phase, so I think it'll only be announced by 2010, and then released in ~2014, probably when Blizzard is done with WoW expansions and content.
So my guess would be:
Diablo III - project Hydra - developed by team 3 (announced in WWI 08, this saturday, followed by a press conference) --> Released around 2010.
Starcraft Online (next-gen MMO) - developed by team 4, still hiring more people --> Announced in WWI 2010, released around 2014, after Blizz releases the 4th and final WoW expansion (probably related to the Emerald Dream or the South Seas/Maelstrom --> one of these will be the 3rd expansion, and the level cap raised to 100 --> a common number for a level cap). WoW probably won't have that many subscribers by then, so they'll transfer a portion of WoW's resources to the Starcraft MMO.
Meanwhile, also around 2014, they release Warcraft IV, which started development in 2010, after the release of Starcraft II in Q4 2008/Q1 2009, and its expansion in Q1 2010.
Warcraft IV continues the storyline and lore from where WoW left off, while preparing the storyline and lore for a possible WoW II.
BTW, Starcraft II and the expansion would prepare the storyline for the MMO.
lol... I think the only thing that everyone on this forum (except you) unanimously agree's up on, is that it is NOT anything Stracraft II related. Can you even provide any rational, or hell ill take Irrational thought as to WHY it would be starcraft 2? The picture, the style of art... everything about it, has NO link in any form to starcraft 2.
You sir, are the embodyment of fail.
Is this an SC2 forum? Why would there be discussion of how it is SC2 related? Just like the PC Action (twice) and PC Gamer, everyone freaks out about change, and it HAS to be about Diablo 3, since nothing else is begin developed by a bunch of other companies. Or the fact that Blizzard has two announced games in production. I'm just saying don't count your chickens before they hatch.
And if you ask me, the picture looks a bit like the crystals from SC that are collected for resources. But that's me not over analyzing a picture.
Is way too friggin obvious. The day is early, and that one has already been noticed and figured out. They had to have expected it. So I think as things start to clear up, elements will be found that relate to all blizzard games.