In principle I support all national groups to achieve self-determination. But as I argued before, it’s not as simple as that in practice (see Isblog, “Self-Determination” Oct 8, 2017). There is a tendency for large Empires to break up. After WWI the Austro-Hungarian and Turkish Empires were defeated and fell apart. After WWII, the British, German and Japanese Empires collapsed. After the fall of communism the Soviet Union’s Empire gave rise to 15 independent countries (Russia, Lithuania, Latvia, Estonia, Belarus, Ukraine, Kazakhstan, Uzbekistan, Kyrgyzstan,Tajikistan, Turkmenistan, Azerbaijan, Moldova, Armenia, Georgia) and Yugoslavia to 6 (Serbia, Croatia, Slovenia, Macedonia, Montenegro, Bosnia and Herzegovina). You’d think there would be space for a few more, but the current two which have declared independence face insuperable odds.
Catalonia has been a part of Spain for hundreds of years and faces significant opposition from the Spanish State. They will be fearful that if they allow Catalonia to go, then the others will follow, such as the Basque region etc. Kurdistan faces insuperable opposition, from Iraq, Iran and Turkey, all of which have significant Kurdish minorities. There is likely to be a war in both cases. Such independence is rarely achieved without a fight, as Israel discovered. The earth is so crowded with competing forces that any piece of it is sure to be fought over. Established countries don’t like to be broken up, they would rather fight a civil war, as did the USA.
In the modern world there is definitely a move towards more compact defensible ethnically homogeneous countries. Quality now predominates over quantity in military affairs, as Israel has proven so exceptionally. Also, with a modern technologically based economy any small country can make it, look at Singapore. It is not difficult to predict that Scotland will move towards independence, ironically to remain in the EU. This could trigger the breakup of the so-called United Kingdom, reversing centuries of English conquest and domination. The world will start to look different.