Fun discussion. Thanks. Anyway, I think you all are far too pessimistic.
Paleo is not just eating wild foods. Few of us even try to eat mainly wild
foods. So questions of the carrying capacity of the Earth for
hunter-gatherers is interesting to speculate on, but irrelevant to our
actual situation. A few rather minor changes in modern diets would go a long
long way towards improving the quality.

Replace wheat with other grains. Wheat is the number one villain in my mind,
the single cause of most of the damage. Replace it with corn or rice and a
lot of the damage goes away. Far from a perfect solution, no grains would be
better, but people will never accept that, for cultural as well as price
reasons.

It would be nice if people ate less sugar and other simple carbs. Unlikely
to happen, they taste too good and are cheap. Really, nothing for us to
worry about except where it concerns our friends and family. It isn't my job
to convert the masses to paleo eating.

Replace badly balanced fats with a better balance. This is happening right
now. I heard an ad on the radio today, a seed company was pitching low
linoleic acid soybeans to local farmers. The benefit is oil that does not
turn to trans fats when processed. Another small step, possibly in the right
direction.

Sure, it would be nice if people stopped eating all that crap, but it just
is not going to happen. So, no shortage of paleo foods for those of us who
choose that path. I expect no price rises specifically for our foods. Prices
will probably fall in fact if more and more people start eating them,
creating more robust markets for farmers to respond to.

One last thing. The population bomb is over. Finished. Dead. Population is
still rising only because of momentum, and recent future world population
predictions are down. 2050 will probably be the year world population
actually starts to fall, according to the studies I have seen recently. All
countries with developed economies have nearly stable or even falling
populations. The US population, for example is stable for native born, and
only rising because of immigrants, who tend to adopt American patterns by
the second generation. Most middle income countries are approaching
stability. Only a handful of the poorest countries still have rapidly rising
populations, and many of those are developing to the point where they will
probably have slower growth as well in the fairly near future.

Developed countries tend not to destroy the environment much, it is poor and
developing nations that do. Reach a certain point, and people begin to start
spending their time and money on nice things, like trees and animals. If I
had a crusade, it would be to help jump poor countries over that level in as
short a time as possible, to limit the damage as much as possible.