Some interesting thoughts on why the world is seeing many cases of increased sub-nationalism (parts of a nation wanting to secede or at a minimum more autonomy): What People Will Die For.
He brings up the point that with increased communication today smaller communities can gel together more easily. Also, in a globalized world it’s more feasible for small countries to function.
There are 2 current examples in Europe: Scotland electing a separatist government and Kosovo pushing to secede from Serbia. Other examples would be Quebec, parts of Pakistan wanting more autonomy, a possible split of Iraq, etc.
These arguments work only to a point. Small countries can still function, but larger, more powerful, countries have more prestige and sway in the world so something else is being lost. Looking at Canada as an example, if Quebec separated neither would retain it’s current level of power or prestige.