Starting with Avengers: Endgame back in 2019, the Marvel Cinematic Universe has told a bunch of different “end of an era” stories. Guardians of the Galaxy Vol. 3 is the latest of these, with a number of the main cast members publicly declaring that this is the last MCU film they’re doing–and writer/director James Gunn has taken over as boss over at rival DC Studios, so he probably won’t be making any more Marvel movies in the near future.
So, yeah, after three of their own movies, two Avengers movies, a Thor movie, and a holiday special, this is the end of the road for this specific Guardians of the Galaxy roster. The group itself will continue to exist one way or another, however, and it wouldn’t be all that shocking to see a new iteration of the group pop up down the road.