“Except that nobody would take that printed Greek money. It would become about as worthless as Zimbabwe currency...if that’s possible.”
If Greece leaves the euro, it will print its own currency, which will become legal tender immediately. Bank accounts will convert overnight. It will be required.
Greece will renounce its sovereign debt at least 5 times in history that I know of. If they do this, they will again offer new bonds. They will be purchased readily, since they will be perceived to have much less risk.
What is unknown is the impact on banks that are now holding greek debt and the impact of a multiple of that debt in derivatives on institutions and world markets.
In any case, it is inevitable that the debt of many EU nations is unsustainable and many will follow - despite the quantitative easing tried.
Any European country with any sense (I know, a vanishing small set) will forbid any bank from owning any Greek notes, either directly or indirectly.