It's definitely a concern to me, and I actually think we're more susceptible to the shortages than the regular person (since we have particular things we want). It all leads back to the sustainability of the Paleo diet for the general population. It's a bit of a niche market, and supply can't meet the demand if everyone wants paleo food. It's good for the few. Not so good for the billion.
I wouldn't hesitate to get back to a SAD in a worst case scenario (although I think we'd be able to mitigate to an extent) if the alternative was starving. In my opinion, while you may feel like crud, it usually takes years to die on the Standard American Diet, it takes a month on the Standard Starvation Diet... :) Of course, that's for me, those with major metabolic problems will have different opinions.
Not sure which articles you've seen, but what I've seen cover the gamut in the last year or so:
1) Droughts, Floods, Freezes - All weather related. All things that have happened in the past before (so it's nothing new per se. Just happening with more people to feed). Causes destruction of the crops, death of the animals, and thus a shortage.
2) Use of food supplies for non-food purposes - Corn to Ethanol.
3) Diseases at the food processing plants causing massive recalls - Salmonella, e-coli, etc. I've seen a lot of bad press on the FDA getting more powers (and various food producers whining), but I hope they put some of their new money into inspectors instead of the usual bureaucratic waste.
4) Pests eating the food (big in India, causing them to have to import food).
5) Overfishing/Pollution. I wouldn't be surprised to see Tuna go away in the next 5-10 years.
Some of the things I think we can do to mitigate:
1) Set up connections to local farmers. It won't help the drought/freeze situations, but could possibly help the outbidding situation.
2) Get more political on food supplies for non-food purposes. The politicians probably won't listen (they get tons of money from the corn lobby). But a lot of that ethanol could be created from non-food supplies. Maybe we're not eating the corn, but someone else is, which reduces the likelyhood of them hitting our suppliers...
3) Grow some food yourself. Mighty tough for me in an apartment, but I'm looking at planting some stuff on the patio.
4) Stock up on long term storable items now, while it's still relatively cheap. I still have a few 5 gallon buckets of rice and beans from the "old days". Not paleo, but beats starving. Look into a dehydrator and dehydrate some beef (there was a post on a cheap build here a week or two ago).
My 2 cents at least.