While Guardians of the Galaxy did really have a completely different tone than we are used to in Marvel films, there was quite a bit that connected it to the larger Marvel Cinematic Universe. Most notably, the introduction of Thanos and the Infinity stones into the movies, something that will be very important in the future.
However, while on a podcast(via ComicBook.com), director James Gunn has once again insisted that Guardians stands on its own. “The last thing I said was something about how the Guardians, we really are mostly focused on creating the Guardians as their own separate universe, creating the cosmic side of the Marvel Universe,” he said. “It isn’t all about leading towards Avengers. We’re not subservient to ‘The Avengers.’ Whether or not at some point, some Guardians and some Avengers meet up and meet somewhere in the world, whether it’s two years from now, three years from now, four years from now, fifteen years from now…I’m not going to say. But ‘Guardians of the Galaxy’ does not exist as a prequel to ‘Avengers 3’ and ‘4.’They have their own thing that they’re involved in. They have their own mythos that they’re involved in. They have their own stories that are equally important.”
Gunn’s not really saying that the two don’t connect in any way, but rather that Guardians isn’t just for building up Thanos and the future of the MCU. The Guardians are their own standalone team completely separate from the Avengers, and their movie doesn’t exist for the sole purpose of developing the story of the Avengers. Their paths may eventually cross, maybe as soon as Infinity War, but for now, Guardians will remain its own thing.
Avengers: Infinity War Part 1 is set for release on May 4, 2018 with Part 2 coming out on May 3, 2019.