10 Outrageous Guardians Of The Galaxy Vol. 2 Theories
4. The Guardians Head To Earth
Although the Guardians are quite removed from Earth's Mightiest Heroes, the sequel is one of the final films before Avengers: Infinity War Part 1, and as such will presumably have some major links to it. We've already seen Thanos in the first film, and it stands to reason that he'll be back in some capacity second time around.
You'd imagine that Nova Corps, and more specifically the orb/Infinity Stone that is in their care, would be an immediate target for Thanos, what with him "doing it himself" now, and that would presumably bring him into conflict with Star-Lord et al.
Although they'd be no match for him, if they learn of his plans then the next step may mean that they have to travel to Earth - something Peter Quill would probably be reluctant to do, so it'd be a last step - to warn the Avengers of what is coming, setting the stage for the first part of the huge showdown.