I use Kotlikoff's software and it's been a great tool for my early retirement. However, in opposition to his point of view, here is what I believe to be true:
1) The US Government is the bank to the world. Similiar to the bank in a game of Monopoly, it is impossible for the bank to go bankrupt. As per the game instructions, if the bank runs out of the supplied money pieces, it can use any substitute as money, i.e. skittles, m&m's, playing cards, or make its own from paper. Either way, no matter what deals the players make, the bank can never not supply the funds for a transaction.
2) The debt will continue to grow in nominal value, and although politicians will use this fact to manipulate the population, it is built in to our current economic system of fiat money.
3) There will always be winners and losers in the economy during both expansions and recessions, but catastrophic failure of the system, I'm not holding my breath. Take the 2008 collapse for example, lots and lots of doom and gloom, but in the end the "bank" produced $700B out of thin air that it didn't have and voila', the system continued on. Same with funding war adventures such as Iraq 2003.
I may be naive and wrong on all this, but that's my story and I'm sticking to it. Been sleeping pretty well since I stopped buying in to all the doom and gloom associated with the economy and government debt.