I don't find this surprising at all, I even like how he's modeling this...I'd agree Earth is fucked, all things remaining equal...Earth is not sustainable to vastly accelerating human beings. All things do not have to remain equal however. I am almost certain that vastly accelerating humans will have hard choices to make, a transition period from what we do now, to new ideas will be difficult, even tumultuous, but as of right this second we have choices. So let's not disappoint ourselves.
Capitalism is successful for our current state of development(in fact, stock markets are highly undervalued), but at some point, it will cease to be useful as our best economic model. I've seen speculations on what this new economy might be, but I have no idea exactly what will come to pass. Of course i have some preferences...or what i think are more likely: