If the governments of the euro area voluntarily give up their national currency – as they have done – and if citizens of the euro area acknowledge the economic benefits of using one single currency in an enlarged economic area, these citizens will start asking themselves why it is possible to have a single currency, but not to eliminate other barriers between the countries of the euro area.
In other words, European integration might become more of a "bottom-up" process, initiated by the citizens of Europe, and less a of "top-down" process driven by politicians and experts, which it is has been so far. Hence, the introduction of the euro will probably give new impetus to the initiatives taken in the 1980s to establish a single market.