The Marvel Phase 3 movies were just announced and there will be a Thor 3, officially titled Thor: Ragnarok. While comic fans know exactly what that name means, as do some who have a knowledge of Norse mythology, the word might mean nothing to others. Here is what Ragnarok means.
Ragnarok in Norse mythology is similar to Armageddon in Christian mythology – it is the end of the days, but in this case, it also means the death of many of the important Gods of Norse mythology. Ragnarok is an epic battle that is destined to see the death of Gods like Odin, Thor, Loki, Heimdal and more.
Yes, Ragnarok is the final battle and Thor is destined to die in it. Basically, at the base of it, this is the Fate of the Gods, the battle that finally ends their rule. In Viking mythology it also marks the end of the world, including Asgard and Earth. The Fenrir wolf will kill Odin, Thor and the Midgard (Earth) Serpent will kill each other, Loki and Heimdall will kill each other.
However, at the end, when the Gods have perished and the worlds have been destroyed, a new world will rise from the waters, beautiful and green, and a single man and woman will come out and repopulate the world and the surviving children of the Gods will rise.
This is all Norse mythology.
There is no way that Thor dies in Thor: Ragnarok, although I think there is a chance that Asgard will suffer. By the end, I see Thor taking the throne of Asgard, realizing there is no other option. It has already been made clear that Thor won’t be part of The Avengers after Avengers: Age of Ultron.
Kevin Feige also said that this movie will be the biggest turning point of Marvel Phase 3, so I can almost see Ragnarok caused by Thanos, which would lead to Thor rebuilding Asgard and then eventually returning to Earth to help save the world from Thanos in The Avengers: Infinity War Part 2.
With Captain America: Civil War kicking off Marvel Phase 3, The Avengers: Infinity War finishing it off and the Ragnarok war in between, this is going to be a very explosive war-filled period for the Marvel Cinematic Universe.