It is such shocking news from the Marvel fans. The team of The Avengers will be definitely different after the sequel, Avengers: Age of Ultron that will be released next year. It has been confirmed by the president of Marvel production, Kevin Feige. He said that the third movies of The Avengers will show new elements which means that the team of the superhero will be different.
It just likes the publishing in which each character will go to their own adventure and then once in a while they work together for a big event. Then they come back to their own comic and it is changed based on the incidents happened.