We have to live with weak GGB for a pretty long time. If the gov. sells their assets in value of $50B, they still would have on their liability side $100B debt (and have to service it for cca. 6-7.0 B/year). So, simply get used to this fact.
At the same time, just by having high-yielding GGB portfolio, NBG is getting a nice interest premium on it; especially compared to German Bunds.
So, would you, as shareholder, prefer to have none of those GGB's? And have Bunds instead?
They actually are benefitting from the Greek debt problem: by getting paid more for holding them.
Anyway, the weak hands have already sold their NBG shares; they will come back after NBG share price is above $5, sometime in 2013.