The Internet is a blaze with Ant-Man news, rumors and updates more than any other Marvel Studios film right now. While one of their films has gone completely under-the-radar with Thor: The Dark World.
Looking at the movie title the question that should hit everyone right away is, what is 'The Dark World' referring to?
We can examine a couple of the Nine Realm worlds like Svartalfheim, where the Dark Elves reside. Or Muspelheim, which is the home of Fire Demons and their ruler Sutur. Or even Niflheim, which is the realm of death and where Hela hangs out. None of these realms really stand out as being 'The Dark World' referenced in the title but there is a place that was seen in The Avengers that was very dark and seemingly a planet of some sort.
Remember the planet that Thanos and his minion were on? That was a pretty dark world in our opinion and could be what is referenced in the title.
Reason we think this could be true is because Loki failed and Thanos' minion, called The Other, said there is no place or realm Loki can hide if he indeed fails at acquiring the Tesseract. Which he did. Now Loki is on his way back to Asgard to be 'dealt with' with Odin and one would have to think Loki will get interrogated and give up the location of where Thanos and The Other are, or were, if they have left that location after their master plan in The Avengers didn't go well.
Then we could see Thor, Sif and The Warriors Three go to this dark world and do some investigating to perhaps figure out Thanos is indeed the mastermind behind Loki's attempt at taking the Tesseract. In turn, this would definitely set up the Guardians of the Galaxy movie the following summer since Thanos is said to actually be in this movie before he appears in The Avengers 2.
This is just speculation but the sequel's new title seems to mirror that dark world Thanos was on in The Avengers so there is somewhat of a connection.
More stories on Thor:
SDCC 2012: Marvel Studios Announces New Titles for Thor 2, Captain America 2 While Guardians of the Galaxy and Ant-Man Movies Coming Too
Thor 2 News: Thanos Rumor Debunked, The Executioner to be Played by Actor Mads Mikkelsen?