Replace "sustainable," and the bit about profit and capitalism, with "efficient" and "corruption and un-free markets," then this is a common right-wing talking point (back when the right wing tried to engage intellectually, at least).

In my unscientific opinion, the current population is unsustainable, and there's no known ways to make it sustainable enough to support the population in the long term (I hope there will be, of course). The most sustainable framing practices are less intensive and result in less output per acre. That's just about survival, ignoring quality of life. I've heard it claimed we'd need 5 Earths for everyone on Earth to live a first-world-like lifestyle. Granted, we should drastically change our lifestyles.

Climate change will also likely lower the human population the Earth can support, and I think we will likely adopt even less sustainable practices to make up for the loss, accelerating our own demise; kicking and scratching and bringing all the ecosystems of the Earth down with us.