Um...okay. I find most people saying this are simply misunderstanding how the checks and balances system works, but I'll give you the benefit of the doubt.
Goverments rise an fall just as surely as the waves in the sea. Its not a matter of if it will fall but when.
There is the when.
You've neglected to account for the how.
The US will not collapse into anarchy, the state system prevents such from occurring. Look to all the other empires that utilized a confederacy model and you will see this. When the central entity collapses, government reverts to the state level. In the US, we have an additional layer, the city level as well.
And there are backups for the backups.
If someone blew up our two main oil pipe lines or our refinerys, trucks would be parked with in a week an the grocery stores would be empty in 2 weeks. What if truck drivers just went on strike?
If someone blew a hole in both major pipelines, the flow would be cut off, repair teams dispatched, and oil back underway within a couple weeks. Truck drivers as a whole will not go on strike, as there are many different trucking companies that work with many different logistics companies, plus the free lance truckers. And there are the trains as well, depending on your location. Sure, the truck system will fail eventually, just as the train system failed before that, and the pony express system failed before that, and the wagon train system failed before that. We are already trying to move towards not being oil dependent, and it will get there, pretty much as soon as the oil companies stop whining and accept their death throes with dignity. There have already been failures of the oil transport systems before, including ruptured pipelines and oil spills. Society is still here.
Sure, it could happen here. But it would not happen overnight, and there is nothing currently happening that would lead to the worst happening in the US. I hear people talking about a 'civil war' coming and the truth of the matter is, unless those folks are given to starting one (and it would be over, fast, with the opposite side being the victor), it just isn't going to happen.
Edited to remove flame