I find this whole incident has changed my view of Spain. I would be thinking twice about investing there and certainly about ever living there after the way that the Catalans have been treated in this.
If the Spanish Government has an argument against Catalonia leaving, present it! There are lots of good reasons why it makes sense to stay together. However, if they just adopt what look like the kind of bully tactics that you would see in some kind of authoritarian state, well then they will simply get the publicity that they deserve.
I am genuinely shocked with the way this has progressed and I think it really shows that Spain hasn't developed into a proper democracy after the dictatorship.