"there are still many options available for Greece and only one for the ECBs["
Exactly. So who holds the strongest suit?
Who has the most to lose?
Greece, which has only pain out to infinity,
or the EU with the following to lose:
Hundreds of billions of Euros (already gone in IMO)
Political power on the eastern edge of Europe. Think what grexit would mean to Europe's hopes in the Ukraine.
A NATO platform
Probable collapse of the derivatives market and financial meltdown
A possibility of contagion leading to a contraction of the Eurozone to Northern Europe only.
Worse still, the possible destruction of the EU.