Well, let's elaborate a bit on the picture, catalonya has always been autonomous to a degree, since this social rift has millenia, centuries and centuries, however during Franco depotism the region (state) suffered a lot of repression in terms of language etc… had to that mix a spanish central government which inherits Franco ideology and has not a solid standing (3 elections to form it and no majority), had to that silence from the government for several decades over this matter, had to that the fact catalonya is supporting almost solo the debt of more than half of spain... and finally sprinkle in top of the cake the fact rajoy is a fucking bastard that ordered police brutality on people voting...
Yes it's secessionist all the countries divides are by norm inconstitucional, what is that point worth aniway in the matter?
This either goes slowly and calm down noone does nothing, either goes smart and catalonya destroys it's economy and makes Spain go bankrupt forcing the EU to make it solve the issue or get expelled, either goes really bad and some groups start agitating things and they get civil war.
Any of those things are not that far fetched seen the history of the place.