This is what I predict will soon befall us:
1) The federal debt now exceeds $10 trillion.
Adding unfunded Medicaid, Social Security, Medicare, veteran's pensions, and similar obligations,
the total is $59 trillion, or $516,000 per household (http://en.wikipedia.org/wiki/United_States_public_debt).

2) The USG will continue to spend on wars, empire, "stimulus packages", "new deals",
and industry bailouts without limit (thus adding even MORE to the debt).

3) As our foreign creditors come to realize that such a debt can never be paid, they will cease lending to the U.S.:
http://www.speroforum.com/a/17305/US-debt-approaches-insolvency,
http://www.atimes.com/atimes/Global_Economy/KA09Dj02.html
http://www.washingtonpost.com/wp-dyn/content/article/2009/01/09/AR2009010902325.html

4) Unable to obtain funds by any other means, the USG will drastically increase the money
supply to finance it's debts and spending (thus triggering hyperinflation).

5) Imports are greatly curtailed, as few are willing to accept payment in a teetering currency which loses value daily.

6) The people will rush to purchase real assets before the dollar is rendered completely worthless,
first emptying/closing the banks, and then the stores.

7) Without access to banks, most businesses will be unable to make payroll and be forced to close
(including food distributors and trucking companies).

8) Food distribution will break down.
The people will seek food from local sources, but will find that very few such sources still exist today.
This will lead to a massive disaster far worse than the last Great Depression:

In the 1930's, there were family farms everywhere (many of which were near self-sufficiency).
Today, the few farms that do exist are extremely dependent on technology and supplies from outside sources.
If a critical part breaks that can no longer be replaced (see below), or fuel and/or grain supplies are disrupted, the
farm shuts down.

In the 1930's, technology was relatively simple.
Most machines were composed of basic parts of limited number (the great majority of which were manufactured in the US).
Today's machines are very complex and are composed of a huge number of parts from all over the world.
Thus, the failure of one part manufacturer (or the cutoff of their imports) can easily trigger the failure of all who depend on that part
(example: http://www.sfgate.com/cgi-bin/article.cgi?f=/n/a/2008/12/26/financial/f113411S39.DTL&feed=rss.business).
And this problem extends to power plants (which is why I stress the importance of a water filter).

In the 1930's, the US population was around 125 million.
Today, it is 300 million.
So even if we all knew how to live off the land, it is questionable as to whether the land could
sustain so many without the super-efficiency of today's modern/highly-technological farms.

In the 1930's, we had a strong manufacturing base (and thus were not dependent on imports for our very survival).
Today, we make virtually nothing (and have largely forgotten how to do so).
Hence, it will be extremely difficult to "boot-strap" our way back to prosperity.

In the 1930's, people possessed incredible know-how:
They knew how to build and repair things.
They knew how to farm.
They knew how to hunt and dress game.
They knew how to preserve food.
How many of us posses such skills today ?

In the 1930's, we were generally a moral people.
Few resorted to violence or theft to get food.
How will today's Americans (many of whom feel "entitled" to everything) will respond when hungry ?