I think they will not leave EU. Becouse it will be a collapse for a european union. It's same like one of the American states would leave USA. EU counsil will not allow that.
they can remain in the eu without being in the euro
Of course they can leave the Euro but when T was saying he was for a greexit a few years ago, now he is not talking about it. He is waiting for the last minute because he thinks time plays for him.