The end of Phase 3 of the Marvel Cinematic Universe is in sight and recent indications have been that the MCU will be in for quite a shake-up when that happens. Now, we have our first hint at which franchise will be taking the lead when we get there. According to Marvel Studios head Kevin Feige, it looks like the plan may be for the MCU to give more of a focus to Marvel's "cosmic universe" in Phase 4, as such, it appears that the Guardians of the Galaxy will be playing a big part in setting that up.
I think it's a little early to know what it's going to look like. I think things are going to look very different at that point, but I think the early discussions we've had with James [Gunn] about Vol. 3 and beyond with what we'll call the 'Cosmic Universe' and the Guardian characters is very exciting. Which is why he signed up and we announced that even before Guardians Vol. 2 came out.
Just before James Gunn began the press tour for Guardians of the Galaxy Vol. 2, the director made a very public announcement via social media that he was officially signed up to direct Guardians of the Galaxy Vol. 3 as well. Currently, Spider-Man: Homecoming 2 is set for a July 2019 release, just two months after Avengers 4. As such, it appears that film may actually end up being the close of Marvel's Phase 3, leading Guardians Vol. 3 to be the launch point for whatever comes next.
These comments by Kevin Feige to Fandango double down on earlier statements that have implied that what comes after Phase 3 may not necessarily be simply a continuation of the characters that we've known before. Perhaps, a focus on the cosmic universe of Marvel means that the plan is to leave all of the Earth based heroes alone entirely, or at least mostly, which has been the MCU's focus to this point, and use Guardians of the Galaxy Vol. 3 as a way to introduce several of the outer space based characters that Marvel has in their pocket, but have thus far gone mostly unutilized.
The idea would make a lot of sense. Many of Marvel's big names are seeing contracts expiring at the end of Phase 3. We would not be surprised to see at least some of them actually die between now and Avengers 4. However, even if they live, if the plan is to see the character take a break for awhile, having Marvel movies hang out on Earth for a long period would cause fans to want to see those characters appear. By taking the bulk of the story to entirely new places and ignoring Earth, at least for the most part, gives Marvel a reason to not bring back Iron Man or Captain America.
Marvel's cosmic universe certainly has a lot of opportunity for new stories, but it will certainly make for very different stories.