instead of this wall of text from my friend at the chaos theater, here is a spoiler. A word of warning though, if you haven't seen any of the movies prior to Age of Ultron, then please see them before reading. if you have, then this will make a lot of sense.
So, if you follow the Marvel cinematic universe (MCU) then you know that there are so far three phases that are leading up to a grand event (posted below), which will be the Avengers: Infinity War.
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Now you're probably wondering what exactly were the first two phases. Well, they are the ones that lead up to the events of the first Avengers movie and all mainly focused on a certain hero. Phase 1 focused on Iron Man, kicking off with his first movie. Phase 2 was all about Captain America. Now, Phase 3 has a number of super hero debut movies coming, but it actually has a lot of focus on Thor. First came his movie, then Thor: The Dark World which took place after the first Avengers. Now, with the showing of Avengers: Age of Ultron, the movie actually set up
A LOT of stuff. One movie it set up is Thor: Ragnarok. For those who don't know, Ragnarok is actually a prophesied war between the gods, which will bring an end to their world. This is what Thor's vision was all about in Age of Ultron. With Odin dead and Loki still at large, this will lead to another fight between Thor and Loki. With Thor being Odin's one true heir, this means he will be the one to lead Asgard in the battle.
Now, in the comics, one main event in the series is that during the war Thor and Loki will both die. But, that's not where their story ends. Due to a series of strange events the two will be brought back to life.....as females. I want to hurry up through this, so I won't really go into details.
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So anyway, I want to move on to the next movie to come out in the MCU which is Captain America: Civil War. The story with this series is that after the destruction caused by Ultron, a new law is to be passed that requires all super heroes to register themselves and reveal their identities to the world. Iron Man and some heroes agree, Cap and others don't. Now with constant disputes from both sides, a war does soon break out. But, there is still one hero who plays a neutral role in this all and will play a HUGE role in it all. That hero is Spider-man. Now, recently the script for CA: CW was leaked and from it, we can see that Spider-man INSTANTLY goes with Stark. He's reluctant to reveal himself to the world, but does eventually. Later, he'll realize that all along, he was manipulated by Stark and will find his way to Cap. And this right here, is what I think is what will kick off Phase 4, if there will be one.
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Now, so far, each phase has been focused on a certain hero because of certain events. What I think MCU is planning....is a Spider Verse series. Why? Well, with the new Amazing Spider-man films, Spidey has quickly become popular again even more since the first three. Now, there is no talk about a third ASM movie, but we will have a new guy play Spider-man in Civil War.
"But the new Amazing Spider-man movies aren't apart of the MCU."
I know. But, I feel like the guys up at Marvel have been planning something since the first ASM. People weren't happy with Toby McGuire being replaced with Andrew Garfield and are begging to have him back. But, now Garfield is going to be replaced in Civil War. And that's when I thought of something. Marvel doesn't just CHANGE the star for no reason. Even if the actor is sick of the role, they always manage to convince them to continue. So that's when I figured, they're planning for a Spider-verse.
So you're probably not familiar with the Spider-Verse series. It's a recent story from the Amazing Spider-man series that plays with the multi-verse theory. The story starts by telling about a family of inter-diminsional super beings known as the Inheritors. They travel through every universe feeding on the most powerful beings in exhistance. It's only then that they gain the attention of Spider-man, who is saved by Cable and explains whats going on. The two then begin to gather any Spider-man/woman not killed by the Inheritors in order to fight them.
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But, what does this have to do with the actors who PLAY spider-man in the movies? Well, it means that they're all versions in different universes. ASM is still in the MCU. Though it seems that what happened in the Avengers has nothing to do with him, it's because it didn't happen in his reality, thus is why he's played by a different person. The Spider-man to being in Civil War is in this particular universe for the sake of plot. This is why me and others hope to see Toby, Andrew and the new kid all together soon in a possible Spider-verse movie.