The Eurozone and the European union are two separate entities. Highly doubtful the EU is finished, the Eurozone might be restructured though, as Germany and France are suggesting (more like hinting). We will just have to wait and see.
As for your Italy reference, Italy can pull through this quite easily if they cut spending. Italy has a strong tax base and good revenue, unlike Greece, which is almost 80% service based economy. 40% is govt employed. Once the tourists stopped showing up so did the revenue.
The US is not even nearly started to be anywhere nearly finished. When America is repeating the Carter years, then repost this.
also, on China saving the US, you do know that Chinas growth is directly tied to the US. They know it too.