I ate this breakfast a few years ago, in Paris, after Europe had converted to the euro. If you look carefully, you can see on the bill tucked under the tray two prices: the euro price and the franc price. They printed them both for a while, to get people used to the new currency.
The euro could be dead in 5 years. A Greek bond default is inevitable. Faltering economies across Europe -- and sluggish growth in the economies of France and Germany, who are required to prop up everyone else -- might put too much pressure on the euro.
I'm not sure a euro collapse would be good for us. Disruption in currency markets never is. But I think it would be bad for Europe. On the other hand, in the short term at least, it would mean a strong dollar, which would make that Cafe de Flore breakfast suddenly a lot cheaper.