Okay, here's the thesis. Sounds like neo-Malthusianism.

> Seriously though, no matter how efficient we get with our space, eventually we'll hit a wall and the solution is going to be exactly the same as it always was and is: reproduce less quickly.

Yep, that's the Malthusian endgame. Unpacking this claim, it seems to be claiming that the Earth is a closed-system that we can't escape. Now I'm looking for evidence or supporting arguments that prove that.

> The only difference is how much nature will be left when we get to that point.

What exactly does the phrase "how much nature will be left" mean to you? This is too hand-wavy, especially for such a heavy-handed conclusion.

> I've started to look at houses with yards as miniature nature preserves.

Is a golf course a nature preserve? No. Of course not. It's an extremely controlled environment. Any wildlife foolish enough to try to inhabit it that doesn't fit in a coffee cup will almost certainly be chased off, trapped or killed.