I am not saying there are no shortages. Of course supplies are limited. What I mean is that if one resource for a certain function or need is used up, another resource will take its place. Take the example of peak oil. There are many types of fossil fuels available and I don't see us running out any time soon. Another example is peak phosphorus. If we run out of mineral sources of phosphorus, industry will mobilize to start recycling manure or harvesting phosphorus from the ocean (where it is all ending up right now anyway).
“Although it was the middle of winter, I finally realized that, within me, summer was inextinguishable.” — Albert Camus