The Greek central bank is not the US Federal Reserve. It cannot print its own currency to buy domestic bonds. It may only offer euros to buy its own government's debt or the private debt of its domestic banks. Greece cannot print euros, so as long as it is confined to the euro it must force bank depositors to accept cramdowns as part of any bank recapitalizations. Forced buy-ins won't go over well with Greeks who remember what happened to depositors in Cyprus banks.
I recently predicted that either a Greek exit from the euro (aka Grexit) or an ECB-driven bailout were the two most likely options. I still do not believe the Greek government will back down from its political pledge to end austerity. Europe just kicked the Bank of Greece where it hurts. The bank will have trouble walking for a few days, until it is forced to announce a bank recapitalization plan that starts a run on Greece's private banks all over again.
Full disclosure: Bearish position on the euro; long put position against FXE.