Are the much mentioned euro bonds feasible?

Comments on Martin Sandbu "Shaking off Europe's German bonds", 18/08/2011, http://www.businessspectator.com.au/bs.nsf/Article/Eurozone-debt-crisis-eurobonds-markets-yields-Germ-pd20110817-KT3T8?OpenDocument&src=rot

While the argument that size matters is reasonable enough, the use of the US and Japan as example needs some caution, because each has its own advantages that are not just limited to their sizes.
Japan first. How much of the Japanese government bonds is has been bought and held by funds and people outside Japan? My answer is likely to be: not much and its share is small. If that answer is correct, then it shows the Japanese are different in some key aspects in terms of their portfolio investments in Japan and abroad, as opposed to most other people in the west. It is the Japanese they themselves buy their low yield government bonds.
Now the US. It is true that it has been the largest economy and also a very large government bonds market - that is, its size is large. However, its political influences and its role as the leader of the west world also have a significant effect beyond the size of its government bonds market.
Ignoring these characteristics of Japan and the US is likely to make the argument and conclusion questionable.

Of course, another consideration is whether the individual states of the USA need to issue their own bonds or can they use the federal government bonds to finance their own debts.

One needs also recognise the further difficulty that the euro zone or EU have a looser structure than the USA. Would the key members that are in a better state be willing to subsidise other members so explicitly?