According to James Gunn, Guardians of the Galaxy: Vol. 3 will set up the next few decades of movies in the MCU.
Thus far, the heroes in Guardians of the Galaxy and Guardians of the Galaxy: Vol. 2 have been separate from the rest of the MCU.
“One of the things I’m doing with creating Guardians of the Galaxy: Vol. 3 — it will take place after the next two Avengers movies — and it will help to set up the next 10, 20 years of Marvel movies.
There is still a long wait until Guardians of the Galaxy: Vol. 3 with several more films to come first.