Yeah, I agree that type of "symmetrical" arrangement will never happen. I'm surmising they will either have to come to a one-sided arrangement where fiscal autonomy varies amongst different countries, or Greece (and others) will have to leave the union eventually.
Is this a hard choice? Actually, I suspect that the choice isn't hard at all for Greece. I imagine that the Greek people would be among the easiest to convince of such a change, if it happened in a fair way where all countries are treated equally. If Greece were not treated like a vasal state, but instead simply as one of many countries that together give up some rights to a central democractic Euro government, that might well be a price that the Greek people are willing to pay for recovery within the Euro.
But good luck trying to get the Germans and other northern countries to agree to something like that.