The Marvel Cinematic Universe hit something of an endpoint with Avengers: Endgame, but the story overall is still moving forward. One set of characters we know are going to have at least one more adventure are the Guardians of the Galaxy. Of course, due to the fate of Gamora in the last two Avengers movies, Guardians of the Galaxy Vol. 3 promises to be a somewhat different affair. We have no idea where James Gunn is going to take the story. Avengers: Endgame co-writer Stephen McFeely says that was exactly the reason Gamora's story was left as it was.
Time travel brings Gamora back from the dead but after Tony Stark saves the universe, we never see her again. A deleted scene revealed a sequence that would have shown Gamora walking off alone after the battle, but since that didn't make the final edit, it means that didn't really happen. It seems that bringing Gamora back, and leaving her fate vague, was done so that James Gunn had as many options as possible when writing his own script. According to McFeeley...
There are the parts so that [Guardians of the Galaxy Vol. 3 director James] Gunn could do whatever he needs to do that. That was just basically, you saw the behind the scenes stuff where they all kneel and she sort of boogies off set. If you let that in, you would've gone, 'Oh, she's alive and she's over there.' It's very vague now. I don't know what he's going to do with it.
The fact is, as far as we know, Gamora perished with Thanos' troops and didn't actually survive. Her entire fate is left vague, which means if James Gunn wants to make the next Guardians movie about the rest of the characters reacting to her death, he can. If wants to make the movie about the Guardians trying to help Gamora adjust to her new life, they can do that too.
The Marvel Cinematic Universe movies all affect each other in various ways. We're mostly led to believe that the filmmakers of each movie have a lot of freedom to do what they want, and the next group of filmmakers working with a given character largely just have to pick things up wherever they were left off. However, it seems sometimes decisions can be made to at least leave specific possibilities open for the future. Stephen McFeely tells Comicbook.com that he's glad Avengers: Endgame didn't end everybody's story.
I also liked that little dangling piece of time travel. The bow wasn't completely wrapped up and there was a little bit of an after effect from what they did. That doesn't necessarily affect this movie, and I don't know how it's going to affect the coming Guardians, but just leaving some strings, when you're tying up this many strings, it's satisfying to know that there are a few still still dangling.
Avengers: Endgame could have given us a more definitive spot for Gamora to end the movie, but in not doing so it gives James Gunn freedom to place her going forward. This, almost certainly, will help Guardians of the Galaxy Vol. 3. Now if only we knew when we might see that movie.