Expanding the Trees
What are the chances that various language trees will be extended in the future? I've completed the French tree (along with some work done elsewhere) and I still feel like a beginner. I've completed the Japanese tree, and if I didn't already know the language, I don't think I'd even be able to pass the N5. Duolingo seems like a helpful tool when beginning a language, but I wish it was useful beyond the very beginning stages.
Both Spanish and French, as well as German, have definitely had their trees added to since they were first released. Some have been tweaked (with small additions) more than once.
I know this, because after completing a tree, new lessons were added (and my completion owl disappeared), and I had to go back and do quite a number of skills and lessons to "re-complete" my tree.
It's been a while since that last happened, so I don't exactly how many skills and lessons were added to each tree, but I think German had the most additions, and it took me a couple days to do all the new material. There were several totally new skills, and many other skills had one or two new lessons added in. But there were also quite a few additions to the Spanish and French.
And judging from comments over the years, other trees have been expanded as well, I believe Norwegian is one example, and possibly Dutch as well.
That said, I agree with your statement, that any of the Duo language trees could stand a bit of expansion/reorganization. It don't think it would be too time-consuming to add another skill or two or three once a year, perhaps based on user requests for certain vocabulary.
I think it's up to the volunteers, though, and other than glory and thanks from the users, there may not be much in the way of incentive for that hard work.
I feel the same way with swedish, I downloaded an app called Drops that gives extra words and there's so many more words that could be added in an expansion. I know they are hesitant to do so because the more complex sentences and words take alot more time and effort but I think there is still plenty of basic words to learn