Whats great about Spider-Man in the comics is he is the everyman. He sort of gives the reader a chance to interact with the other characters, what would it be like to meet Wolverine or Captain America? And its fun to see him teamed up with someone like Wolverine who is the opposite of himself and see them get along so well. But thats not needed in the movies. Unlike comics the movies only have a short amount of time given and some of the time is needed to establish the characters and the premis and the rest of the time is for the story. If you bring in a character like Spider-Man into the Avengers then it becomes like Rogue in the X-Men movie or Jubilee in the X-Men cartoon, it becomes the team being introduced through his eyes and then HE has to have a reason for being there and it becomes a Spider-Man movie. If all the Marvel characters were in the same movie universe and you could guarantee (spelling?) the same actors and costuming and such for every movie that would be a different story. Then again, you could bring in Spider-Man in a team up fashion. The Avengers are fighting someone in New York and suddenly Spider-Man swings along to join them... OK that would be a cool movie.
Captain America is fighting a bad guy, and Spider-Man swings in and gets drawn into the fight and suddenly he is dragged along in this deep super villain plot (like the Net) where he didn't even mean to be there and suddenly he and Cap have to figure a way out.
Maybe Marvel could figure out how to do Marvel Team-Up Movies.
exactly. Though... I do think the avengers should always have one founding member in it.. (preferably Cap, ironman, or Thor) and i wouldn't oppose a recast of them either if the actors didn't return. I think the hardest one for the audience would be RDJ leaving... but if they like everyone else... why not?
Thats why I would stagger the roster rotation. So that by the time Chris Evan's contract is up and he leaves playing Captain America and never looks back the audience already is used to and knows the characters of Ant Man and Wasp, so that they become the new heart of the team. So the audience wont see a completely new cast in Avengers 4, and not know who they are or why they should care. They would care because Ant Man and Wasp are there, the audience cares about those two because of the last Avengers movies they were introduced in and they care about the new Avengers brought in because Ant Man and Wasp care. Then when Ant Man and Wasp leave, because the actors contracts are up (and actors don't usually like to stick around too long after that) you bring in more new Avengers to replace them. So you can bring in Black Panther and She-Hulk. But the Avengers brought in in the previous movies become the new heart of the team.
Just an example:
Avengers 1: Cap, Iron Man, Hawkeye, Thor, Black Widow, Hulk, Nick Fury, Hill, Coulsen
Avengers 2: Cap, Iron Man, Hawkeye, Thor, Black Widow, Hulk, Nick Fury, Hill, Coulsen... Ant Man and Wasp
Avengers 3: Cap, Iron Man, Hawkeye, Thor, Black Widow, Hulk, Nick Fury, Hill, Coulsen... Ant Man and Wasp... and maybe one or other character like Black Panther.
Avengers 4: Ant Man, Wasp, Scarlet Witch, Quicksilver, She-Hulk, Wonder Man, Black Panther, Vision, Agent Gabe Jones.
Avengers 5: Black Panther, Scarlet Witch, Quicksilver, She-Hulk, Wonder Man, Vision, Agent Gabe Jones... Mocking Bird maybe, Tigra perhaps, Hercules, Valkyrie
Avengers 6: Scarlet Witch, Quicksilver, She-Hulk, Wonder Man, Vision, Agent Gabe Jones... Mocking Bird maybe, Tigra perhaps, Hercules, Valkyrie, Luke Cage, Iron Fist, and Jewel...
Etc.
Eventually you could even bring in Beta Ray Bill, Thunderstrike, Bucky as Captain America, War Machine, etc.
This way if any actors wants out they just replace him/her with a logical and comic based plot idea... like on Dr. Who. If a actor playing the Doctor wants out they have a fail safe plot to get him out and replaced with a new actor and the audience wont question it. These actors have been signed on for about 3 movies, plus cameos in other films like Fury in Iron Man 1 and 2, Captain America, a solo I think, and the Avengers. I hear Evans is signed on for something like 9 movies (3 Caps, 3 Avengers, maybe 3 other films) or something but those include cameos too. I doubt he will stick around to do more Cap movies after his contract is up.
But these are my Avengers movie ideas for keeping the franchise going long after the original actors have left the movie, this is a thread for the FF movies.