> We may yet discover that Malthus was right.

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