There are four parallel threats to the present buoyancy in share prices: a messy resolution to the eurozone crisis, with Greece defaulting on its debts and tumbling out of the euro; a further abrupt reversal in bond markets; a renewed rebound in the oil price, prompted by growing geopolitical chaos in the Middle East; and a hard landing in China, a still very real possibility which everyone in Europe seems to have forgotten about amid the ongoing standoff over Greece.