The Guardians of the Galaxy began as the introduction to the space corner of the Marvel Cinematic Universe, and that's a niche that they've largely occupied on their own. Up until next year's Avengers: Infinity War, the team's stories have been isolated from the Earth-based events of the MCU, though writer/director James Gunn says the crew's next adventure will be kick off a new story for the whole enterprise.
While answering questions on Twitter, Gunn clarified some comments that producer Kevin Feige recently made regarding the MCU's third phase. Specifically, that the upcoming Infinity War will conclude one story and then begin another.
1/2 No. Read Kevin Feige’s quotes & not the static around them. It’s the end of one long story & the beginning of another. https://t.co/NA1f0EnQeE— James Gunn (@JamesGunn) October 16, 2017
Naturally, Gunn couldn't reveal what the "other story" will be, but he did say that Guardians 3 will be one of the films that kickstarts the new story for the MCU. The film is currently being written by Gunn, who has also signed on to direct once more.
Guardians of the Galaxy Vol. 3 is slated to arrive in 2020, but the characters themselves will appear in Avengers: Infinity War, due in theaters on May 4, 2018. Chris Pratt, Zoe Saldana, Dave Bautista, Pom Klementieff, Bradley Cooper, Vin Diesel, and Karen Gillan were reprise their respective roles as Star-Lord, Gamora, Drax, Mantis, Rocket Raccoon, Groot, and Nebula.