I think that there is a big difference between natural resources and total wealth. The main reason why the world's wealth is increasing in modern times is not because we're using up more and more resources but because of technology. Technology allows us to get more utility out of the same resources - a computer now is far more useful than a pot made five thousand years ago out of the same raw materials was then; a genetically engineered plant (including selective breeding) produces twenty times the usable food for twice the nutrients and the same amount of effort. While natural resource consumption will inevitably hit the latter half of its S-curve, technological progress will continue and accelerate without any currently visible limit.