Stratfor has an interesting article about how European states could splinter into regional groupings. It is the most politically divided continent on the planet and political unity has a lot to overcome.
This doesn't eliminate the importance of NATO in at least setting some minimums for standardization for coalitions of the willing for specific military missions even if the alliance as a whole won't commit to them. But it is interesting when you consider that unity required the Soviet threat to push the continents many pieces together. Without that threat, unity is not a primary goal of many countries.
Actually, what strikes me about Europe's divisions isn't that they are divided but that others aren't. China, in particular, is a country-sized continent that could easily become divided politically, could it not? Might we not one day come to think of "China" in geographic terms the way we speak of "Europe" today? Europe isn't on the road to political union and will likely go backwards on that front. Might not China go backwards, too?