There has been a tremendous loss of diversity in the food supply in the last century, thanks to the triumph of hybrid varieties, bred often for high yields and ease in shipping rather than disease or drought resistance. This graph illustrates what has been lost:
A fine article from National Geographic on the subject: http://ngm.nationalgeographic.com/2011/07/food-ark/siebert-text
These are folks who have been working since 1975 to preserve the ancient varieties of seed:
How terribly frustrating, when real wealth is abandoned for the sake of false wealth. Yeck. But, as you say, the seed savers are out there, and the diverse varieties will be needed in the years to come, so with some dumb luck they may make a comeback. I’ll certainly be doing my best to see that they do! Good link, Uncle.