The world has changed tremendously since WW2 and Europe has radically evolved beyond all recognition. If you're thinking of a conventional war fought on European soil, then no, providing there aren't mass revolutions, that just isn't a realistic possibility nowadays.
Greece is a very sad case and it has everything to do with the economic situation. Much of the electorate have lost all faith in all forms of Government in that country and increasingly voters have turned to the far-right in despair. It is often stated that the problem with Greece is, put simply, it implemented high living standards and high levels of infrastructure spending (schools, transport, hospitals, social welfare arrangements, leisure facilities e.t.c) with poor
fiscal management. Matters such as a large amount of uncollected tax, low pension ages and an excessively large public service workforce are all part of this.
With the whole financial crisis, many Greeks have suffered immensely. People who were once in secure teaching positions are having to go to soup kitchens to feed their families. That's a huge negative change in your life. Obviously, people are looking to apportion blame. Without delving too much into the whole economics of the Eurozone, most in Greece blame their own past governments for not keeping a tighter control of collecting taxes and revenue spending. Of course, people weren't necessarily thinking about that in the good years of cheap and accessible credit!
Some now also blame the EU and more specifically Germany for the austerity in the country. That's because the EU and Germany has insisted that major cutbacks take place because of the financial bailout that has been/will be provided, which have been extreme but arguably essential to keep the country afloat. I am by no means an expert on this issue, but I do wonder if that had led to this support for the far-right. My personal view on this is that the Euro currency was a political dream and was not based on rational economics. To assume that Greece has as strong fiscal management as, say, the Netherlands was as silly in 1999 as it is now. However, that is digressing slightly.
Basically, what I am saying is that far-right support in Greece is down to the very poor economic situation there that has arisen out of the whole Euro debacle. People have experienced massive falls in living standards and have lost faith in and/or have anger towards the more mainstream parties in Greece. It's not about territorial disputes or racial discrimination and I don't think it signifies any sort of nationalist trend that will sweep Europe and polarise nations.
I am no expert of course, but the above is just how I see the situation...