Let those places grow feral again. We don't need to take up the entire damn planet as a species. Or at least the entire "fertile" bits of it.

I could not be more diametrically opposed to your position. It's clear to me we have far too many people as it is, and the only way out is through population decline. Anything else is ridiculous line noise to argue about. Once you solve the CO2 climate change problem you have about 10 other just-as-bad crises right behind it if population growth continues.

Sure, as you say there could be some more black swan events in science/technology that technically lets us expand in the short term much like modern agriculture has. I don't see that as a positive as it simply delays the inevitable and makes it even more impossible to recover from.