(Btw. I believe switzerland is not trying to be self sufficient anyway, but donimport lots of stuff, like most other countries do)
Other variables to factor in would include cultural/esthetic ones: how much would a population tolerate a reduction in the idyllic/scenic nature of their landscape, merely to accommodate crops for a rising population?
(This is what I referred to as "quality of life" in another post.)
And that "how much would a population tolerate a reduction in the idyllic/scenic nature of their landscape" is a very arbitary factor that will strongly depend on who you ask.
Those things ain't absolutes and human society is not made up of numbers and not calculable. So you can make approximations. And they can be useful or not. But you cannot calculate the perfect size of a human society. That is just arbitrary.
Ah yes, folks fighting the good Malthusian fight since 1798, and yet to see a win. LoL. [1]
We may yet discover that Malthus was right.
Then what??
https://eu.boell.org/en/SoilAtlas-soil-degradation
https://earth.org/95-of-the-earths-soil-on-course-to-be-degr...
https://www.fao.org/about/meetings/soil-erosion-symposium/ke...
We may also discover that einstein-rosen bridges exist [1] or that aliens exist or that magic is real or that astrology works. Hopefully none of these things are keeping you up at night.
Also, broken clocks, twice a day right, etc etc. Clocks still broken.
> Then what??
Plenty of dystopian sci-fi available for your reading/viewing pleasure. [2]
[1] https://en.wikipedia.org/wiki/Wormhole
[2] https://en.wikipedia.org/wiki/List_of_dystopian_literature
You're ridiculing subjects you clearly don't understand.