I don't see anything in the world right now as sustainable.
Not the political situations.
Not the issues of overpopulation and mass immigrations.
Certainly not our poisoned planet.
And the fact there is no foundation of facts anymore. Since the Renaissance human society has been built on a foundation of certain truths and science. That's rapidly disappearing.
I find that more and more people are having the same intuitive sense that you have that we've entered the end of this age of man.