Avengers: Age of Ultron will introduce new characters to Marvel's Cinematic Universe, as well as rumored to be killing off certain characters. Thor's third film "Ragnarok" will have it's plot penned in a similar fashion.
Ragnarok in Norse mythology means a series of apocalyptic events that will lead the the world's destruction - and the movie's plot might be exactly that: the destruction of Asgard.
Movie Pilot explains their version of the plot:
"Thor does not take Loki's treachery lightly. He runs out of patience with his trickster brother, and literally rips his head from his shoulders. However, Thor's rampage does not end there. When he discovers that Asgard is doomed to fall and be reborn endlessly, he decides to literally cut the tapestry of time - allowing the citizens of Asgard and the rest of the universe to make their own decisions, rather than being prisoners of fate."
They also report that Thor's actions will also bring him to a path of destruction making him "unworthy" of his power, speculating cutting time and space will ultimately lead to his own death.
Thor 3: Ragnarok is the second to the last movie before Avengers: Infinity War, reported to release in 2018.
Before Ragnarok, which releases on July 28, 2017, the hammer-wielding hero will appear in 2015's Avengers: Age of Ultron starring Robert Downey Jr. reprising his role as Iron Man along with Chris Evans as Captain America and Mark Ruffalo as The Hulk. Joining them are S.H.I.E.L.D. operatives Black Widow played by Scarlett Johannson and Hawkeye played by Jeremy Renner. Completing the team are fellow agents Nick Fury played by Samuel L. Jackson and Agent Maria Hill played by Cobie Smulders. The Avengers must once again reassemble to defeat James Spader as Ultron, a rogue byproduct of Stark Industries, hell bent on destroying the human race.
