With Marvel Studios recently announcing the title for The Avengers 3 and The Avengers 4 to be "Infinity War," it's been speculated that Guardians of the Galaxy and its sequels will somehow directly lead to the two movies.
That appears not to be the case as director James Gunn recently took part in a press QnA where he basically says Guardians of the Galaxy is its own thing.
There is further good news in that James Gunn stated Guardians of the Galaxy is more about leading to more Marvel Cosmic movies.
I don’t feel beholden to that stuff at all. I think it’s really about the Guardians and what they are doing. We’re not subservient to the Avengers. “Guardians 2″ is not a movie that’s made to move toward “Infinity War.” It’s something that’s made to move toward future cosmic movies, so I don’t feel that that is something that affects me that much.
Regarding future cosmic movies, high on fans' list of characters to see in the Marvel Cinematic Universe is Adam Warlock. Gunn did previously state the cocoon seen in the Collector's lair belonged to Adam Warlock, and now he further talks about the character.
Well... [hangs his head] yeah [room laughs]. There’s a cocoon that’s exactly like Adam Warlock’s cocoon. I wasn’t really thinking that much when I put that in there. That was my call. They were asking me, “What should we put in it?” And so I went through the Marvel Handbook and just picked cool things that looked neat to put in the boxes, and one of those things was Adam Warlock’s cocoon, so now everybody thinks he’s out of there. I don’t know [laughs].
Another fan-favorite character is Richard Rider Nova. What is interesting regarding Richard Rider is that without him, there would not have been a Guardians of the Galaxy comic book, and hence the $700 million plus movie. Marvel Comics relaunched Marvel Cosmic with their Annihilation event back in 2005/6 which had Richard Rider at the forefront. Rider ended up with his own series, with the next Marvel Cosmic event following, Annihilation Conquest. That's when Guardians of the Galaxy was born (or reborn, if you will). Rider was also in an earlier version of the Guardians of the Galaxy movie script, and Gunn's film did feature the Nova Corps.
Speaking of characters, James Gunn did also mention characters from the first movie he would like to explore in the second.
Yondu and Kraglin, the Ravagers. And I love Nebula. I think that she is underutilized in the film. I want to see more of her. The Collector.