The extend and pretend policy might actually work(to prevent defaults). They are essentially guaranteeing the liquidity of any country for any length of time, meanwhile these countries are doing austerity which should result in a fiscal surplus, at that point the country can keep going without a default. This comes at a severe cost to the economy(which means ECB keeps rates low for years and years) but it can be done
The question is wont the riots, revolt and unemployment make the politicians change their mind at some point, that would lead to defaults. But so far, there is little or no evidence of that, politicians if anything seem to be holding the belief that a default would lead to a Lehman style meltdown quite strongly(Perhaps correctly so)