One of the advantages of being more flexible than a 50 foot carnivorous neoreptile is that we should be able to realize we're consuming our resources irresponsibly without having to run out of them first.

As for our ability to live off the land, I believe it is highly compromised. The Inuit now need snowmobiles, rifle cartridges and Gore-Tex parkas to hunt their traditional game, and not many deep desert Bedouins can still live off camel products and an occasional oasis. And how many farms, even in our MidWest, still have a team, a plow, and the skills on hand to be able to grow their own food. (Remember that chilling last Jim Burke "Connections" episode?)

I think the only human communities on earth that would have a sufficient concentration of skills to survive a civilization-wide collapse would be the villages of India. The average village family still knows how to grow its own food and fiber and weave its own cloth. Wouldn't it be ironic if civilization was once again confined to the Indus River Valley?