While I know the graphs are just supposed to represent the idea that human population and our ability to sustain a given population grow at different rates, I think they are misleading.
http://www.google.com/publicdata?ds=wb-wdi&met=sp_pop_grow&idim=country:USA&dl=en&hl=en&q=population+growth+for+united+states#met=sp_pop_grow&tdim=true
The above shows that the world at large doesn't really follow anything resembling exponential growth for the human population (or at least the number of tabulated people slowed down), and you can check out the stats on individual countries in there as well, as well as juxtapose them against one another. It's neat. I'm fairly confident that less developed countries will have smaller rates of growth if/when they reach the Holy Grail, known as the Consumer State.
As for our ability to produce food to support our still significantly (imo) growing population, that is a bit more complicated. I think that food prices might become an issue for certain nations, and the availability of food is already an issue in certain places (Africa, mostly). Should that become "too much" (whatever the hell that means) of an issue, I think the solution would be to cut down on livestock farming. Livestock farming consumes a rather large amount of all crops produced, and the returns for cutting down on even a relatively small percent of commercial meats would translate into cheaper crops, as well as more of it. I'm not a vegetarian, nor do I feel a lot of compassion for animals, but farming fewer of them would be beneficial in certain circumstances.