As Duedal says no big deal. It's their problem. The same goes for Britain, Denmark etc. It's their problem and no big deal for the rest of us in the Euro.
What amuses me about the whole Euro debate, particularly in Britain is the dire warnings about what would happen if they join. Meanwhile in the Eurozone everybody is just getting on with it, the economy hasn't collapsed, no one has lost their national identity. Such much for the disadvantages of joining the Euro.
Sweden and the UK have little in common, Sweden is a high tax, high cost, welfare state while Britain is a low tax welfare state.
What Sweden and the UK do have in common is an attitude that they are better than the rest of Europe in everything they do. So no Euro. What they also have in common is the fantasy that their own government and bank controls their currencies and interest rates. The fact is that there are now two main currencies in the world. The Dollar and the Euro.
Both will join the Euro in due course, probably after damage has been done to the economies.