@Pachylad:
oh wait it turns out it may just be 'an epilogue series'… sigh I guess you're still right for now Robby 
I conceded back when the movie was announced, that that explained everything about their multi-year silence. That if they had planned a regular season of another 25-50 episodes to immediately follow season 5, (and do a White Diamond arc properly instead of cramming it into like 4 episodes) then that would have needed to start work on it, and had no reason to not announce that deal, to their fans and stockholders and network schedules, by comicon 2016 or so, 2017 at the latest.
And whenever it airs, it is however going to be 2 or 3 years after the previous season ended, (depending on if you're counting Reunited or Change Your Mind) so it wasn't in the pipe when I said it wasn't in the pipe, they were not working on or planning on it in 2016/17 when everyone swore there was a season 6 coming immediately based on an offhand comment from a VA of the brazillian dub..
Movie announcement in July 2018 changed the rules though. No formal season announcement, but they could keep doing special easier to promote things for a while (and since they kept doing it in bombs anyway it changed little.) It explained them not announcing a sixth season but also indicating that they were still working on stuff.
This is a string of episodes very clearly separated from season 5. Even has a movie between them. It counts as season 6. Unless its really, really short 4-8 eps at which point yeah, classify it as a miniseries, but it should still count as season 6 even then.
So, right and wrong. I'm happy to be wrong! Even if it is just a limited bit more.
But looking at episode counts (season 5 has an extra 8 episodes), how Reunited seemed like a season finale, and how long it took those final episodes to actually air, (7 months) I still think they had planned for six seasons, only got 5, but were given a few more episodes to wrap the story up. While negotiating deals for movie and this epilogue, which were dependant on ratings and other tie ins. That's pretty much the only thing that fits and makes sense, including why the White Diamond arc was sooooo rushed compared to how leisurely the show usually goes.