All the optimistic interpretations require a decrease of real users, which is not desirable
I completely agree. I do not find the current level of growth encouraging, though apparently Dan has some data that paints a different picture. I asked him for more detail, and it will be interesting to see what that is if he provides it.
My only disagreement (or perhaps questioning is a better word) with your interpretation is whether the issue is less growth in real users (bad) or a decline in user participation (also bad). In reality it is probably some of both, but I do feel you have been painting too harsh a picture on the latter, especially when you presented the chart from Dan's post without accounting to any meaningful degree for the issues both he and I have identified with it (fake accounts, antispam system changes, etc.)