Right now this Catalan elite has been voted into power by the people, and if there's something that these politicians have made clear from the start is that they were going for a referendum full steam ahead. Catalans have voted for these guys, and whether they are right or wrong, or neither, the people are partially responsible by proxy. That's what makes all of this particularly difficult to solve.
That's taking into account quite a few variables that don't really mesh with the weak EU we have today, namely that a lot of countries would have to agree to certain terms only to silence a small region of one of their members. In Spain especially, EU confidence is six feet under among the population (voter turnout in EU elections is abysmal), and while it may be a noble goal in spirit, where does it leave the Catalan region in the grand scheme of things? Part of an even larger and centralized entity with even more power to silence their voices. Also, the EU forming certain power blocks won't sit well with other smaller peripheral countries, and the EU might end up solving a small problem and ending up with a huge one.
Possibly the most reasoned approach overall, and if there had been a situation like this in the first place probably none of all this would have happened. Constitutional reform is inevitable in the long term, and it should have been tackled earlier. What I'm not so sure about is the omission of the PP from all of this, which unfortunately is the most voted party in the country and we all know how "flexible" they are when sharing power and negotiating. It's a bit of a deadlock really: It can't happen with them and it can't happen without them.
That might work if the economy really gets better fast. Last week the Spanish government took out a 100 million loan to pay the pensioners, not a great sign of economic recovery from the looks of it. Unemployment is catastrophically high with no signs of improving. The housing market is slowly creeping into another bubble, largely driven by foreign investment/speculation and shooting the prices (especially rental) through the roof. People with careers in STEM and the likes are literally fleeing the country since investment in research and development has been simply eradicated. There's also an aging population that will heavily burden the health and pensions system increasingly over the next few years. I hope I'm wrong and it does get better, but the prospect is pretty bleak right now.
Alternatively, the Spanish government could agree to a popular vote that could involve:
1 - Leave everything as it is.
2 - Better economic deal for Catalonia overall, and the exclusion of the Spanish government from all "cultural" decisions like language etc. The previous gutted Estatut could be a starting point.
3 - Carry on with independence.
Everybody knows what option would win, and it would probably end this once and for all for years to come. Even if it's ultimately smoke and mirrors (the independence option isn't legal so it's moot), it would undoubtedly calm a huge part of the population for a comparatively small compromise on behalf of Spain: A bit more cash and don't touch the language.