... institutional investors and sovereign wealth funds aren't going anywhere, there's simply nowhere else to park that much money for so little risk.
True but only for a few more years. If, and it's still a big if, Europe gets its fiscal house in order there will be viable alternatives. Should that happen and the US still refuse to undertake structural entitlement reforms we'll lose our present status as the safe haven of choice rather quickly.
S&P has been dead set on downgrading U.S. debt for at least a month, largely for political reasons.
False. S&P is a donk playground with nearly 3/4 of its political campaign contributions going to Democrats. All of the US ratings agencies lean left as judged by their contributions but S&P leans the farthest. They trapped themselves by demanding a $4T deal (which was political & intended as cover for Obama to demand tax increases) for the US to avoid a downgrade, what little credibility they have left would have been shot if they hadn't followed through when Obama called their bluff.
Plus: it's the spending stupid:
Bush II was a profligate spender and wildly irresponsible but Obama is upping the public debt of the US at a rate more than 4x faster than did Bush II.
And I'll reiterate, there's a truly free market that prices a French default as 3 times more likely than a U.S. default, yet France still has an AAA rating and is not on a credit watch.
France must, at least in theory, adhere to the 3% of GDP target set by the EU. They're above that now but their annual deficit has been coming down more quickly than anyone forecast and even French socialists believe they're on track to run a surplus and begin retiring public debt by 2014.
Ditto Japan although the picture there is more bleak: even with the post-tsunami reconstruction spending binge they believe they're on track to balance their budget by around 2020.
Compare & contrast that to the US where we're headed in a direction that will see entitlement spending consume the entire federal budget in a few short years absent massive structural changes to those programs. Not only do we not have a credible plan to balance our budget, Democrats refuse to even discuss changes to the programs that will, by themselves, destroy us if left unchecked.
That said the downgrade was indeed a joke but only because everyone on the planet with a couple of brain cells left to rub together already understood, and has for some time, that the US is definitely going over a financial cliff and that there will never be sufficient political will here to stop it before it happens.