I believe we'll see it within the next few(2-5?) years. And I think it will be worse than the Great Depression. I'm thinking on the scale of Yugoslavia in the mid to late ninties. The problem I see is not a lack of food or water, humans are resourceful and could have community gardens, livestaock, etc. The problem is, we aren't that kind of society anymore. We lock our doors because even when the economy is GREAT and almost everyone has access to the basics of life, there are a LOT of people out there that don't respect the sanctity of a man's home or even human life for that matter. These people are commonly known as gangsters, but it runs much deeper than that.
Gangsters are just the ones that society points out every day in the media. The others (and I generalize as society has done with gangsters b/c I know a few that are not violent, they just like the life and I can't understand it) are known as bankers, lawyers, politicians, millionaires, etc. There are MANY people in this country and world that could really care less whether you or I live or die. If they are hungry, they aren't going to plant a garden or trade for a cow. They're going to try to come and take MINE. It's easier, faster, and more profitable. Yes, I said TRY. I'll do my best to defend my family. They might win in the end, but it's going to cost them dearly.
Anyway, THAT is what I see as being the biggest problem. While people DO starve or die of illness during financially hard times, the world hasn't seen anything like the show that's going to go down here in the US. I'm not HIGHLY educated, but am not stupid either. My opinions are just the stoned observations of an everyday Joe in the Engineering field (when there's work).