James Gunn has made no secret of the fact that he loves Rom: Spaceknight, but the kid's toy turned Marvel superhero has a complicated right's issue that prevents him from joining the Marvel Cinematic Universe, as the character is owned by Paramount while his fictional history is an intellectual property owned by Marvel.
"Yes, I love Rom. [But] I don’t [see a Marvel produced Rom movie happening] because this is the problem- Rom, the story is owned by Marvel Comics. So the Dire Wraiths, you know, all that story is owned by Marvel Comics. The character and the toys are owned by Paramount, so you can’t have both. Now you can’t have the Spaceknight, at Marvel, and you can’t have the Spaceknights without the story. What always interested me was more the story of the Spaceknights. People who gave up their humanity to save their planet was always very interesting to me, so there may be something to do with that, but it won’t be with Rom."
Would you be interested in seeing a Spaceknights movie that doesn't include Rom? Could this be a clue to where Guardians of the Galaxy Vol. 3 is headed? As Gunn stated, the fictional planet of Galador and their conflict with the Dire Wraiths are all intellectual properties owned by Marvel. It would likely be pretty easy to tell the same basic story of Rom - just with another Spaceknight (such as Terminator, Starshine or Firefall) taking his place.
The group is involved in a number of cosmic storylines in various Marvel Comics so it genuinely appears as if their inclusion in the MCU is a matter of "when" not "if."