European Switzerland?

Ever since they rebelled against the Holy Roman Emperor centuries ago, the Swiss have held themselves aloof from the rest of Europe. In fact, with non-EU Switzerland a fiercely independent enclave surrounded by EU members, the map of Europe looks rather like, well, Swiss cheese. Now the voters of Switzerland have opted in a referendum to become part of Europe's passport-free zone, established by the Schengen Agreement and Dublin Accords. It is interesting to note that the nay-saying cantons are within or near the nucleus of the original German-speaking Swiss Confederation, while those western cantons favouring the measure are relative newcomers. If the Swiss should ever bring themselves to join the EU outright, will they in effect be rejoining the Holy Roman Empire? It would certainly be one of history's great ironies.