Mathematics represents the rational skeleton that upholds and stabilizes our vague, formless but far more common belief-based thinking.
Without it, losing it from neglect, we would collapse back into a pre-rational state of fantastical, wishful thinking.
Pretty much exemplified by large parts of US society already, but there is no bottom otherwise keeping society from collapse.
> What would such a world look like?
Major religions, minor religions, cults will have a field day. Or more like a field century or a millennium or twenty, who knows.
Up to a few years ago, I would see or read some science fiction that was medieval times with spaceships (ala Dune) and I would roll my eyes and think “ffs, can’t people move on and invent something more original?”. Now I seriously believe that’s one of the most benign futures waiting for our species[^1]. Not that there aren’t lots of lights in this tunnel, it’s just that its shadows are very black.