Not sure about that, why would bankers be interested in keeping a single currency? How it helps them?
You have to ask yourself who has benefited most from bailouts and huge QE. Is it the people or the banks? Bankers have funded wars and countries going back hundreds of years, its good business for them.
QE is possible without a single currency. For example, if Germany had its Deutsche Mark and no ECB above that, their central bank could also make a QE.