Even if this never happens, Sony won't always hold the film rights to Spider-Man (probably after this trilogy is completed), and Marvel/Disney will retain them and create their own incarnation of the character. They don't believe in reboots, so no origin story. Although many will say "no, that will never happen," they can't keep making Spider-Man movies forever, and they need to make at least 1 film every 5 years to keep those film rights. I assume the plan is to milk the Spider-Man character as much as possible, and then sell him over to Disney where they can include him in their films. So perhaps within the next 10-15 years.
Technically, Marvel starting over with a new Spider-Man continuity when/if Sony gives back the rights is still a reboot. Any movie that discards previous continuity and does its own thing is by definition a reboot even if the movie doesn't redo the origin. Both
The Incredible Hulk and
Punisher: War Zone are considered to be reboots even though they're both not origin stories.
I have a new theory! Now this is a longshot, but I think one of the reasons Sony wants Spider-Man in the MCU is because it's becoming somewhat customary for superhero movies to be set in a larger universe now. Marvel has the MCU, DC is going to have shared universe with there characters, and even Fox is going to have a universe between the X-Men and The Fantastic Four. Spider-Man would be left out, and would be limited to stand alone films. It's not a big deal, but it would be understandable for Sony to be nervous. There only option would be to make a universe between Spidey and Ghost Rider, and we all know that will never (and should never) happen.
That's still a rumor at the moment. DC/WB most likely has no clue at the moment whether or not they want to do a shared movie universe. They did say they didn't want to originally but the recent success of Avengers may have made them change their minds. Knowing WB, they'll probably wait to see how Man of Steel does before doing a shared universe. That is if Man of Steel is even capable of fitting into a shared universe seeing how they keep talking about how realistic it is and how Superman will feel like the only hero in the world.
That's not true. Guardians of the Galaxy is in the MCU, but none of the Guardians will be in The Avengers. So the premise of the MCU is not for heroes to team up necessarily.
There is a huge chance Thanos or another galactic character will appear in both franchises though. That's how they'll probably get connected to the Avengers.
I have my own theory on why Marvel and Sony would want Spider-Man in Avengers and on why Marvel would be doing a Guardians film. They already introduced Thanos and the Infinity Gauntlet - it had a cameo in Thor, for those who don't know - and remember that in the Infinity Gauntlet big event Marvel had, it was all the Marvel heroes in general that had to fight against Thanos.
Marvel might want the same thing for the movies and thus before they unleash Thanos in live-action, they're probably trying to expand their universe as much as possible with as many characters as they can (that they have the rights to, of course) while trying to get the permission to use some of the characters they don't have the film rights to such as Spider-Man. It's not that big of a stretch IMO. Almost every Marvel superhero has been in or fought alongside the Avengers at least once in the comics. As long as Avengers 2 or 3 or whichever Avengers sequel they plan to do this in doesn't have too many characters in it to the point where you won't get a chance to develop them, this shouldn't be a problem.
There is one thing though that I do fear for Spider-Man if he does appear in an Avengers film. Someone said that Spidey is too big of a character for Avengers and I think that is true. Notice how whenever he appears in an Avengers book or in a big event, he is usually used as comic relief. That is not the way I want to see him get treated. Another problem you might run into with having Spider-Man in Avengers that I just thought of while typing this (lol) is that many people will complain he was underused. He is Marvel's most popular character and most people will be excited for him the most and will want him to play a major part (just like how Iron Man being the most popular character in Avengers was one of the factors to why he saved the day in the end) but at the same time, you can't have Spidey play too big of a part because he was never a big-shot in the Marvel universe to begin with and doesn't carry the weight Iron Man, Cap, and Thor carry. I'm not saying you can't have a well written Spider-Man in Avengers; just that it's going to be difficult. But then again, a lot of stuff originally seen as difficult to do was pulled off very well by the MCU.
I would personally have Spidey be one of the major factors to why the day gets saved in the end but in a way that doesn't undermine the other Avengers. I would do it similar to how Iron Man saving the day in the first Avengers film was done. People throughout the film called and regarded Tony as just an *** with not a care in the world who doesn't play well with others and wouldn't be willing to do a very heroic act. He proved all of them wrong in the end when he was willing to almost give up his life to save the city. I would do something similar with Spidey. He is seen as your loner average Joe with superpowers that fights street crime in the Marvel universe and no one would expect him to be the guy that wins the fight in the end and risks to almost lose his life in doing so. And once again, this should be done in a way so that it doesn't undermine the efforts of all the other characters. After all, Tony's heroic moment at the end of Avengers didn't undermine the rest of his teammates either (at least not in my opinion).
t:
. lol just kidding.
