(The following are from comments by readers on Zerohedge.com)
Short answer: Nothing happens (but you knew that)
Long answer: Current law requires a budget ceiling and a vote to raise it. Violating that law would open up violation of other similar laws. Not too far down the path of similar broken laws, the states start printing their own money. In US dollars. At which point hyperinflation ignites and the USofA ceases to exist as a functioning union. Much hilarity ensues.
The monetary system of the world (not just the USA) is based upon the illusion that there will always be greater fools available to pay the last greater fool.
The only reason people remain in the room that's about to be flooded with poisonous gas is the complete and utter belief (supported by group think and conventional wisdom along with healthy dollops of denial and self interest trumping rationality) that each person can get out before the gas can over come them.
As long as the majority continues to believe in the lie, the lie remains solid and fully formed. Thus the illusion is reality because the belief (and by extension the actions) of the people makes it real. One of the realizations one has when looking at this philosophically is that reality is simply what the majority says it is.
The banks are stable despite horrendously convoluted and distorted balance sheets and non-performing assets simply because the government says they are and people want them to be. Thus they are. If a rule or law threatens to upset the illusion, it's changed to conform to the group think.
What most people don't understand is that this "reality" is extremely fragile and will fail quickly. The Fed, Treasury and the President understand this extremely well. This is why this is considered a National Security issue and every lie, theft, payoff and Ponzi is encouraged and endorsed at the highest levels. Our reality is supported by a lie and thus by extension is a lie. Since there is no more real support under our economic reality, every effort must be extended to support the lie.
Do or Die! Seen from that point of view, everything that's going on is perfectly understandable.
The lie holds until the first person breaks the pact and heads for the exit. It takes no more than one. Then the stampede erupts because while nobody wants to be first, everyone wants to be second.
I think California is that "person" at the sovereign level. As goes Cali, so goes the nation, so goes the world and in rapid fashion. We will see, come summer, if Cali stays within the illusion or bails.
Someone pointed out this video as metaphor for our current situation:
Cunning lions await the herd as it lumbers forward, trustingly, behind their dear leader. If divided, the weak in the herd are slowly picked off, unless...
Anyways, if someone has a better explanation to what would really happen, send it to me!