I think the Gunn era projects will be all (or most of them) interconnected and lead into each others like episodes of a series. They are trying to replicate the MCU formula, so having characters introduced before having their own films has to be expected.
I hope it'll turn out something like that, and there is a SM villain among the main antagonists. Not just doing a SM vs The Authority movie.GOTG 2 starts off with the Guardians versus the Ravagers, and I think here we will see Superman vs. Stormwatch. Ego shows up and tries to recruit Quill because he needs another Celestial to help activate his seedlings, and I think Brainiac likewise will appear and try to recruit Superman to help him. Maybe Brainiac gives Superman the basic pitch of “hey I only bottle cities from planets that are doomed to try and preserve some remnant of the species” or Brainiac might be Kryptonian himself and try to appeal to Superman through their shared heritage/legacy. Just like how Quill finds out Ego killed his mom, Supes finds out Brainiac bottled Kandor and fights with him over it. Superman wins but Stormwatch gets destroyed and the Authority rises from the ashes in time for their movie, which I expect Superman will be in.