Take a look at this video: http://fora.tv/2007/01/26/Why_Foxes_Are_Better_Forecasters_Than_Hedgehogs
I know it's long but it's got some thought provoking material. The short summary is that hedgehogs (people who view the world in terms of one big idea) are more likely to make incorrect predictions but occasionally they pick up on a major development early, while foxes (people who keep a sort of bag of tricks of different ideas) tend to make better predictions, in part by gathering up ideas from hedgehogs.
I think that you are a classic hedgehog. You primarily view the world through a lens colored by your concern for issues of economic liberty. I will further add that I believe you are correct in your identification of the trade offs involved in social welfare functions in government and you are a faithful advocate of the importance of one end of the trade off.
I don't think you're right about the collapsing scenario, at least not yet. There are definite concerns about some functions being unnecessary or inefficient at the federal level, although in other cases, the deficits the federal government is experiencing are a symptom of macroeconomic deficits which I'm not sure that we currently have any options for addressing. We suffered a drop in our income but the cost of our needs continues to rise.
As it happens, I work as an actuarial analyst in pension consulting. Everyone has a fundamental actuarial liability for the income they will need to live should they survive to be too old or too disabled to work. You can fund this liability yourself by saving for this eventuality, although going this route you will bear all of the longevity, inflation, and investment risks and there is a significant chance that even if you practice diligent saving and safe investing that this money will not be sufficient. If you have a pension, your exposure to these risks is reduced. Pension related shortfalls reflect the adverse impact of these risks on the backer of a pension.
The unfunded pension liabilities we are seeing right now are due to recent investment losses combined with an increasing difference between average lifetime and average working lifetime. However, these factors affect every single person who does not have a pension as well. A person who does not have a pension is effectively the sole backer of their own personal pension. Or maybe you can regard their friends and family who may be called upon to support them backers of their pension as well. The underfunding of retirement is much more severe than you realize and this is one of many problems we face competing for resources.
(For the record I personally advocate for a policy that pursues funding retirement through a combination of social security, pension plans and personal saving in a manner such that someone who completely forgoes personal saving or loses their savings would need to cut back on their standard of living significantly, but not unachievably so. There are pension plans which exceed this standard which may consider cuts, although the impact of plan design on the employer's staffing requirements also needs to be considered.)
Returning to the original topic, my expectation is that both the federal problems you highlight and the broader structural problems will play out more slowly than you, hedgehog, expect and given the current lack of policy options to address the broader issues it may be necessary to concede a current priority of simply surviving in the short term while some other matters develop. There are some prospects for a revival of the growth of American GDP and if that comes to pass there will be substantially more breathing room on the broader structural problems.
There are also some problems brewing in other countries and I'm not sure if they will harm the US or if they might create opportunities for us. China's demographic crisis due to it's one-child policy has yet to play out. Japanese and Chinese nationalism is on the rise and could lead to some form of indirect conflict between the two of them. India has its corruption problem and has been passing laws to limit foreign investment. Europe still hasn't come to terms with the fact that the Euro was a bad idea. There's always the possibility of countries in Africa of reaching a turning point where economic development speeds up in the same manner as it died for China and India.