In an interview with GQ magazine, Chris Pratt revealed that not only is he contracted to appear in at least two more Guardians of the Galaxy films (whoo!), but that he was also on with Marvel Studios for even more beyond that. He said:
... I'm tied to doing three more, or five more, Guardians of the Galaxy or whatever it is, you know. Two more Guardians plus another couple...
And while that's not the clearest sentence even constructed, it would appear that we should expect two Guardians films as well as two-- or three-- more beyond that.
This is excellent news, as his portrayal of Starlord played a significant role in making the first Guardians film so enjoyable. Knowing that he will be appearing in future Marvel films is a good sign that the studio is looking to shift their focus further into the cosmos-- and the following six films are a good bet as to where they might take the MCU's favorite famous outlaw-- and hopefully, his entire gang will be along for the ride.
1. and 2. Avengers: Infinity War
This one is almost a guarantee. The first Guardians film was the also the first to feature Thanos in any major way (his brief Avengers post-credits scene doesn't count), so it would be a crying shame not to see the Guardians of the Galaxy confront the Mad Titan in some way during the course of the two films. Chances are, the Guardians will feature in one film and not the other-- either they appear in the first film as an initial barrier for Thanos on his way to conquer Earth, or they appear in the second to aid the reeling Earth-bound heroes and deliver the final cosmic plot device necessary to defeat the villain. Splitting their role in the overall war over the two films would be a convenient way to add some balance to what is surely going to be an already sizable cast of characters, and would help to limit the number of contracted appearances used up on the Infinity War for Chris Pratt and the rest of the Guardians.
3. Captain Marvel
Of all the current and future Earthbound heroes in the Marvel Cinematic Universe, none seem more likely to make the journey into space than Carol Danvers, the hero of the upcoming Captain Marvel film. Danvers's powers are the result of being exposed to an alien being, so whether Marvel decides to have Carol go to space or the alien go to Earth, it seems utterly likely that the character will have an opportunity to cross paths in some way. We know that her solo film is scheduled to appear in between the two Infinity War films, so perhaps her role in the story is that she is sent as an emissary from Earth to try to rally other worlds to defend her planet from destruction at the hands of Thanos. She would then meet up with the Guardians (likely liking their wounds from whatever chaos Thanos has had the opportunity to wreak upon the greater galaxy at large) and brings them back to face him again in Part II. Starlord meeting another Earthling for the first time in his adult life would be a great moment for both characters, and let's face it: once the world witnesses a Starlord + Captain Marvel + Gamora love triangle on celluloid, nobody will ever need to see another.
4. Planet Hulk
Speculating a little further out of the box, let's first examine the challenges standing in the way of a Planet Hulk film being made. First, Universal Studios own the rights to any Hulk solo film, meaning that he can only appear as part of an ensemble cast. In this proposed version, Hulk would really be the villain of the story. But wait, you say, how could Hulk be the villain in his own movie? Well, let's address that second setback to making a Planet Hulk movie.
In the Planet Hulk comic, most of the supporting cast is made up of characters that Marvel studios doesn't currently have the rights to include. The Silver Surfer makes an appearance, but is owned by FOX as part of their Fantastic Four franchise, with the same being true of the aliens known as the Brood (an X-Men foe). Other than that, Planet Hulk prominently features characters exclusive to that miniseries. By using the Guardians of the Galaxy, Marvel's Planet Hulk could feature an ensemble cast, with the Guardians allying with Bruce Banner to overthrow a Red King, or being forced into gladiatorial combat by an already-reigning Hulk (hence, Hulk as the supposed villain of the film). Hopefully, this would lead to a World War Hulk film that would feature the Jade Giant beating up on all of Earth's Mightiest Heroes as well, but for now, let's imagine Chris Pratt and the rest of his team battling aliens in an intergalactic Colosseum, where Han Solo meets Maximus Decimus Meridius.
Speaking of aliens, do you know who has been spending a great deal of time with the Guardians of the Galaxy in the comic books these days? That'd be Venom, as Starlord and his crew discovered the planet from which the villainous oily costume originated. Putting Venom into Sony's Spider-Man's films hasn't worked yet; Spider-Man 3 saw him entirely mishandled, the victim of a movie already crowded with villains, and whatever plans Marc Webb had for the character's in the Amazing Spider-Man films will now never come to pass. But now that there is some cooperation with Sony and Marvel, perhaps the latter could do some of the heavy lifting in advance of Venom's appearance on Earth in a later Spidey film.
I'd like to imagine the symbiote would make an appearance in Guardians 3, where the crew encounters one on their own ship a la The Thing or Alien, but with jokes and pretty colors. After they blow the thing out of the damn airlock, it is free to go find Eddie Brock on Earth, Eventually, the Guardians discover they let a dangerous adversary go unchecked, and have to finish the job they started.
6. Howard the Duck
Okay, this one is only getting a mention because Howard the Duck made an appearance in the Guardians' post-credit sequence. Since the studio has already shown in interest in being able to switch tones between characters with the release of the much darker Daredevil, maybe making a straight-up comedy could work. I don't know. Hell, let Seth McFarlane do it, since it would basically be Ted in space with a little Starlord and Rocket Raccoon thrown into the...
Wait-a-minute. I don't hate this idea anymore. Oh, and wasn't Al Pacino recently talking about how he wanted to be involved in a Marvel movie? Let him do the voice, of course.
There's dozens of us who would see this movie. Dozens.