The implication is really the other way around. The USD was the reserve currency in part because of the credibility of the US government's financials (and also because of amount of trade, etc). But obviously, the US has taken a huge beating credibility-wise recently.

After all, Sterling used to be the world's reserve currency : things change.

Some other AAA countries: Switzerland, Luxembourg, Norway, Singapore.

To me it seems a little ridiculous that the US and these countries shared the same rating for such a long time. On the other hand, there are AAA countries like UK, France, Germany that do not seem to fit into the same category either.

I have no real opinion if the US deserves the AAA rating, but thinking treasuries are the safest investment in the world seems a bit optimistic.

That's one of the MAJOR implications of this, if I'm not mistaken. Of course, bonds denoted in Euro's or other currencies wouldn't be affected.

There are countries who don't use debt payments as political tools. A congressional stalemate that leads to a failure to pay bondholders is entirely possible.