You're right. The chaos is only temporary. Stasis usually returns in just a dozen generations or so.
But then that stasis is also temporary. Frequently the stasis lasts a hundred years (3 or 4 generations) and, rarely, it lasts 1000 years (30 or 40 generations). But it always gives way to more flux and instability. Civilizations that vanish "suddenly" often take 200 years or more to "suddenly" disappear.
The bottom line is, conditions are never stable for very long. But they remain virtually unchanged over the period of one or two human lifetimes, so the average person never sees any significant change. So, unlike a skillfully edited movie, nobody is born into the height of the empire, lives through it's crash, and survives long enough to see a new order take its place. Great grandfather was born in the height of empire, great grandson and his great grandson thought it seemed that "things are a little worse now than when I was young," and great-great grandson's children took the beginnings of the new order for granted because they were born into it.
That being the case, planning for "the future" is futile. We don't know what that future will be, or how soon it will arrive. Sustainable farming is fine if the climate continues to support it. But it won't. Even in the hundreds of centuries before "climate change" there was climate change. People who build their little self-supporting eco-communities may find, like the farmers of dozens of cultures before stretching back tens of thousands of years, that the way they do farming just doesn't work under changing climate conditions. In other words, perma-culture is NOT "perma" at all. Succession is at work continuously. Grasslands are always in the process of becoming forests, and forests are always in the process of becoming deserts, and deserts are always in the process of becoming grasslands, or vice-versa, or in some different order depending on local conditions and changing climate. Nothing is "perma" in this world.
So the only planning that makes sense is this: "Plan to be flexible. Learn to be versatile." If you want to teach your children how to survive, teach them how to get their food from many different diverse sources under many different and changing conditions. How to plant wheat when the weather is right, and how to fall back on acorns when the weather isn't good for wheat. How to fish when the crops fail, and how to hunt when the fish don't show. How to hunt squirrels when the deer disappear, and how to survive on grubs and termites when larger game is scarce. The one constant throughout all time is that the cultures that had only one major source of food are the cultures that perished when the climate shifted. Versatile cultures survived, even of they didn't always prosper. But rarely did they starve.
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