Of course, senior EU politicians daren't even think about it. Most of them still see Europe's future in terms of the Maastricht treaty's objectives. But as I argued in this column last month, it's odds-on the timetable for European monetary union (Emu) will have to be put back. What happens to Europe then? Is it Armageddon, as German chancellor Helmut Kohl sometimes seems to suggest. I think not.
But my optimism depends on the EU's single market surviving the demise of Emu. The single market is the foundation of internal commerce, designed in the mid-1980s for completion in 1992. There are still many barriers, but they get smaller each year.
Supporters of a single currency say Emu is essential to the single market. True, big swings in real exchange rates in the EU would encourage business in strong-currency countries to press for import controls. But trade flows fairly freely between the US and Canada (and increasingly with Mexico), and these countries have separate currencies. There is a danger that frustrated fans of Maastricht might use the absence of a single currency as an excuse for weakening the single market, but there is no logical reason why they should do so.