After a head-spinning bout of volatility, next week will be dominated by one question: Will the European Central Bank take the ultimate policy leap or pull its punches? The ECB could launch a government bond-buying program with new money as soon as its Jan. 22 meeting, although Greek elections three days later are a complication. With markets in an unusually febrile state – oil and copper have plunged while the Swiss franc rocketed after Switzerland abandoned its currency cap – it’s a fair bet that if the ECB holds back, there will be an extreme reaction.