Leaving aside for the moment the orthodox stages of integration which ascend from a free trade area to a full blown political union, other forms of integration may present themselves if our backs are to the wall. For example, a failing state or barebones survival scenario could precipitate a particular form of integration.
Central banks have been offering real-time gross-settlement (RTGS) systems to the commercial banks for large-value interbank transfers because these systems are required for the settlement of monetary policy operations. Given that the first RTGS systems were created with the aim of meeting domestic requirements, they were rather diverse in nature and not necessarily suited to the needs of a single currency area.