Know what's really funny? As a modern society, we only really *need* something like 5 or 10% of the population to carry out the necessities of living - farming, securing energy supplies and running the power plants as well as water / sewer, etc. We also need a basic police force, some medical personnel, and teachers for the children, although that's not absolutely necessary if push came to shove. Of course, we need people to build houses, make clothes, etc, etc, but if things really got bad, we could go 10, 15, or even 20 years on our existing stock of stuff without producing / importing anything new. (Just make sure you're stockpiled in lots of underwear - I have a feeling this is an oft-overlooked item in prepping...LOL.)
So, to be conservative, I would say a society could hold together, for some time at least, with 20% of working-age population actually working, while the rest are at idle. But of course, there's the problem of how those people will be able to support themselves - as it would surely be impossible to tax the 20% of workers to support the other 80%. So what gives? Let everyone who doesn't work starve? That clearly won't happen without a fight - America will burn long before we see mass starvation.
The only way out of this is to keep most people employed, as well as keeping the income flowing to the retired population. Since the survival of our nation is at sake here, you can bet that our government will resort to any and all measures to keep things going - first by spending ourselves into oblivion, and once that train comes to the end of its tracks (possibly very quickly and suddenly in a dollar collapse), then we'll resort to, um, other means of securing the funds needed to keep people working, fed and housed. Ever heard of the term "nuclear diplomacy"? That's when a nation threatens another nation with nuclear warfare in order to get what it wants - an example would be the US threatening to drop a big one on Dubai unless they fork over their trillion$ of accumulated wealth. And so on and so forth.
In any case, this will not end well for the world - but there's really no other course of action. You either let the majority of the people starve to death, or you start flexing some muscle - it's the law of the jungle, and we will see it applied most likely in the relatively near future.
At least there's a very good chance I won't have to worry about growing old...LOL.

Nowhere to run, nowhere to hide...
...and the meek shall inherit the Earth!