A domestic Central Bank floats the domestic economy according to international market's demand and supply, while on the other hand a federated Central Bank sinks a nation's domestic economy by being inflexibly centrally planned. Each sovereign and independent economy has its own needs. A strong Germany and fiscally responsible nations need a reasonably strong Euro or otherwise they had worked for nothing; and a weak PIIGS zone and fiscally weak nations need to have a weak Euro for monetary and fiscal bullets or otherwise their economies will be entrenched in perpetual spiral of death. There is a strong clash of interests. The conflict appearing as cracks is getting stronger. A new Greek currency that comes with unlimited monetary easing will be able to be used to pay off debts, create monetary stimulus, load the government with fiscal tools, cause the domestic currency to be subjected to real market mechanism according to where it should be and not according to where Euro should be, and spur employment and exports when the currency is cheap.
Short term wise, Greece will plunge into a severe crisis style recession with Greek unemployment rocketing up, its economy in collapse, price of imports sky-rocket and it will be relegated to 3rd world economy.
However, Greek disaster has been priced in 80-90% by the Greek stocks market already. Greek market index has been priced for near bankruptcy too, with 80%-90% value being shaved off from the market already (Peak to Trough). When you are at level -8 or -9 out of level -10, how down can you go? Your economic freefall is just a jump of from -8 or -9 to land at -10. Falling one or two storeys will not land one dead. You won't die compared to someone jumping from a maximum +10 to -10, a fall of 20 storeys. If out of the Euros, Greece will pay everything in new Greek currency and reset its system once and for all. Its new currency will be so thrash that its labour will be so cheap and this will spur a new wave of Emerging Market Industries shifting into Greece which has proximity to the rest of the Eurozone. It may even be the "China" of Europe for cheap factories and cheap production. First to benefit will be its goods, services and tourism industry which will go into superbull. Because of a system reset that degrades Greece into a 3rd world economy if it gets out of Euros, people will be more willing to accept any manufacturing jobs that are accompanied with hardship. No more fake Euro prosperity but real Greek reality as a new form of united Greece forms.
A mass creation of new employment from the ultimate plummet and new currency reset will be the start of a super-cycle bull market for Greece amidst a crisis. A new real bull is often born out of a -10.000 scale FFA bear market. However, if Greece still remains with Euro, well, it will just carry on to be on morphine drip and be supported by artificial clutches, and its supercycle bear will still be with it indefinitely until the day it removes the artificial life-support tube.