Like the major comic book Thor, “the kingdom of darkness” - this is his personal journey where the hero has to solve his own problems without the help of all the other superheroes.  With regard to the second general collection “The Avengers,” he will in 2015, where the team will be a new intergalactic threat. 

Spoiler!!!  Click to Read!: 

Now Marvel Studios vengeance is developing a new scene, which by tradition will stick to the film’s credits.  We did not reveal all the secrets, but there is a good chance that it will eyeliner to the sequel “The Avengers”, because just the other day, Alan Taylor familiarized with the new script by Joss Whedon . 

Spoiler!!!  Click to Read!: 

So, it says the team faces a new intergalactic threat...Ultron?  Intergalactic??  Huh?  lets make a quick list here...
-In the trailer "the fabric of reality is being torn apart"
-Based on the childrens book for the movie, there is a "rift in time and space"
-This article also seems into indicate that the after credit scene involves the Avengers sequel, where Alan Taylor was given the script by Whedon's sequel...

Perhaps Ultron gets created In avengers 2, and he already took over the world?  But due to the events of Thor: The Dark World, Ultron finds himself back in the past?...