There still are a number of legal, institutional, political and even cultural problems to overcome before we can declare this ambitious undertaking achieved. The direction of progress is clear, its speed less so. Banking Union is not an end in itself, but a backbone of the single currency.
First, for money to be truly single within a currency area there has to be full substitutability between its different forms, including full fungibility of deposits across border. Second, risk sharing channels are particularly important for countries in a monetary union, because the single monetary policy cannot cater to cushion asymmetric shocks. The financial system is a central channel of adjustment.