There is a very interesting phrase in the middle of James Gunn's statement about his writing and directing a third installment of Marvel's Guardians of the Galaxy franchise. The third movie, he explains, "will conclude the story of this iteration of the Guardians of the Galaxy." For comic book fans, two elements of that sentence suggests some intriguing possibilities.
Let's start with the idea of "concluding the story" of this version of the Guardians. On the one hand, that's a curious notion, given that there's currently a Guardians of the Galaxy comic book featuring this exact team, not to mention the simple fact that decades of superhero stories have underscored the truth that there's no real conclusion for any character in a superhero universe. But, then again, there is something called the "Cancerverse"…
The version of the Guardians that movie audiences know and love originated in a comic book run written by Dan Abnett and Andy Lanning that launched in 2008, and ran for a couple of years. After the 25th issue of the series, it ended by leading into a storyline called The Thanos Imperative, which seemed to serve as a definitive conclusion to their storyline - and, indeed, ended with Star-Lord permanently removed from the universe altogether. (Of course, this being superhero comics, both Star-Lord and his Guardians were back in action in 2012, but Star-Lord's fate certainly seemed permanent at the time.)
The concept behind The Thanos Imperative was simple: A tear in space has created a connection between the Marvel universe and an alternate universe where Lovecraftian entities had destroyed the very concept of death. That wasn't a good thing, however; instead, living beings - including versions of familiar Marvel heroes - had metastasized into monsters who sought to transform and infect everything in their wake.
Thanos, who infamously worships death, initially worked with the Guardians to try and destroy the so-called "Cancerverse," before turning on them. As the Cancerverse begins to collapse, Thanos attacks the Guardians and the superhero called Nova - a human member of the Nova Corps, as seen in the first Guardians movie - and, at the last moment, Star-Lord and Nova order what remains of the team to leave the alternate reality while they stay with Thanos, distracting him until he (and they) are destroyed by the end of that reality. The storyline finishes with the Guardians disbanding, and being replaced by a new group of superheroes dedicated to keeping space safe from danger.
(Although Star-Lord and Thanos would both reappear in comics a couple of years later, it would take another two years for it to be explained why both weren't dead; the short version is "they escaped before the reality collapsed.")
It's possible that the new team that formed in the wake of that storyline - who appeared in two comic book series called Annihilators in 2011 - could end up being the next iteration of cinematic Guardians of the Galaxy, but a far more likely possibility is that the torch could pass to the original comic book version of the team… who just so happen to exist one thousand years in the future.
When Guardians of the Galaxy debuted in 1969's Marvel Super-Heroes No. 18, it was a comic book series taking place a thousand years from the present day, with the Guardians a team of aliens - each from a world colonized by humanity at some point - fighting back against an alien race dedicated to galaxy domination. That version of the team was the primary incarnation of the team for the next 39 years, and has continued to make comic book appearances since the creation of the contemporary team, most obviously in a short-lived Guardians 3000 series.
While it might seem counterintuitive to place the next iteration of the franchise a millennium away from the rest of the Marvel Universe, doing so could restore the space - no pun intended - separating the Guardians from the rest of the cinematic Marvel universe now that Avengers: Infinity War will bring the previously Earthbound heroes into space itself. Keeping the rest of the Marvel property at arms length has helped Guardians feel unique so far, and if a crossover is really necessary, there's always time travel. And, besides … after 10 years, is there really anyone out there that doesn't want to see the future of the Marvel Cinematic Universe at this point?
Of course, wondering about the potential for future heroes and a movie Cancerverse feel pre-emptive, with the second film still awaiting release next month and the third yet to be written, never mind released. But the confirmation of Guardians Vol. 3 is the first announcement for what would be part of Marvel's "Phase 4" releases - the future is already taking shape, it seems…