Beyond giving us an idea of what these characters were doing prior to the events of Avengers: Infinity War, we didn’t necessarily expect this movie to relate directly to the Avengers films in any meaningful way, but Gunn’s comments certainly imply that it does.
The other interesting thing about James Gunn’s Twitter review is his Pro Tip that everybody should be sure to see Ant-Man and the Wasp prior to Avengers 4.
Whether this is something core to the story, or just a post-credits sequence which contains something interesting, remains to be seen.
This would seem to imply that the new movie will include some important information that fans will want to know before we get to next year’s big blowout.