Good question! And yes, a lot of these changes are not related to the first 3 story campaigns

Overall, some of the biggest internal milestones we have left are working on expanding campaigns 4-6 (ie the Project Alderaan campaigns), as they are not quite fully feature complete yet. Also, given we want to keep the aspects of Project Alderaan a surprise for release, the newsletter update above only has that one vague line about Project Alderaan work, but really that includes a very large amount of time/work.
Overall, while all the ship content and core game are indeed done and stable, we really want the first-time folks play FotG to feel rich and fully formed in the campaigns. Similarly, we always are operating under the assumption that we might only have 1 official release before getting a letter from Disney. To be fair, this assumption seems not as likely, but we don't want to risk it when there are still campaign features left to enhance.

We are striving to make sure this situation does not come to pass, as we very much want to support and keep releasing FotG updates after initial launch!
And indeed, that SW project is really quite cool, and we have had contact with the developer for over a year now! It is really impressive work for just one person, and again speaks to probability of mods/public projects surviving. Though, that project is still new-ish and has a long way to go to be feature complete for a whole game that would make it more noticeable in our opinion (again, the dev is great, it's just that FotG is quite a bit more further along since we have had the luxury of a larger team, the FSO devs, and much more time).