As mentioned, the other two ratings agencies had already downgraded the US debt. Neither of those had much of an affect. So this 3rd one is sort of a forgone conclusion - IMHO.
The US can print the world's reserve currency. What is the likelihood of technical default?
As long as it stays the worlds reserve currency, but you kinda need other countries to get dollars from trade with the US to buy the bonds. Printing money, is inflationary and reduces the profit (or turns it into a loss) on bonds so the threat of printing makes buyers less keen.