I think it unlikely that Catalonia will either get a referendum or independence. First of all, unlike the UK, referenda in Spain have to be organized at national level (whole of of Spain) and not at the autonomous community level (ie. Catalonia). This is defined by the constitution which everyone, Catalans included, voted for when democracy was restored. The constitution can be modified but you need two thirds of the votes in parliament and the Catalan parties have failed to achieve this.

Yesterday the Catalan parliament decided to go it alone, ignore the Spanish constitution and call a referendum in Catalonia anyway. The Spanish government is now appealing to the Constitutional Tribunal which will in all likelihood quash the Catalan law as unconstitutional.

The next likely step is that the Catalan parliament will call early elections which will be fought on the issue of independence. If those in favour of independence win a majority, there is a chance they will declare independence unilaterally and hope for the best. The likely outcome is that the Spanish government will temporarily, as per the constitution, take over the government of Catalonia until further notice.

Most Catalans I speak to seem to think the Spanish government won't dare and everything will go swimmingly whilst conveniently overlooking the following factors:

• The current ruling party, Partido Popular, are the direct heirs of the Franco regime and are itching for a showdown with any independence movement.
  

• The Spanish government has the constitution and the law on its side even if they are slowly losing the moral argument.
  

• No European country or major nation has given support to the Catalan indepence movement. Not surprising since it would set a precedent for their own minorities and no goverment in its right mind would give support to an anti-constitutional movement in a peaceful, democratic country.
  

• The EU has consistently said that any breakaway state would have to apply to join the EU as per  the (Maastricht?) treaty. This application would need to be approved by all 28 member countries so if Spain vetoes it, Catalonia stays out. This explains why the SNP was extremely cautious about mentioning the Catalan issue as they were very conscious that Spain would in all likelihood veto Scotland's re-entry in the EU just to show the Catalans.
  

Now let's assume the Spanish government doesn't intervene and accepts Catalonian independence. As previously mentioned, Catalonia would be outside the EU and without a Central Bank to lend money to its government. In order to pay civil service wages the first measure of the new Catalan government would be to shut down the banks and ATMs, take a certain percentage of money out of all bank accounts to avoid bankruptcy. This is what happened in Cyprus, a EU member, a couple of years ago. Catalonia would eventually have to create its own currency (using the euro in the long term would be almost impossible) which would most likely be devalued overnight.

As far as the economy goes I'm fairly certain most Catalan companies would  struggle to sell products in the rest of Spain and could face border tariffs to sell to the rest of the EU. I suspect all those companies that could afford to, would move their manufacturing plants to Aragon or Valencia. The rest would struggle to keep going since the Catalan economy is largely export-driven.

A practical example would be Barcelona FC. Most Catalans are under the impression that this team would go on playing in the Spanish league as "the Liga wouldn't be worth anything without Barcelona FC". The Liga would certainly lose a bit of interest but I suspect Barcelona FC would rapidly go bankrupt on the pittance it would earn from playing in the Catalan league.

My final comment on the issue is that if the Catalan goverment feels free to trample the Spanish constitution for its own selfish interest what validity will a Catalan constitution have? Any "democratic" group (a town, region, expats...etc) within Catalonia would be able to use the precedent set by the Catalan government to go it alone.

Having said all this the Catalans do have legitimate grievances that are being ignored by the Spanish government. The PP in particular has made it an electoral strategy to bash the Catalans in order to gain more votes elsewhere in Spain. Frankly, both sides of the debate are being selfish, bloody-minded and blithely ignoring the consequences of their actions. In a word, they're being Spanish about it...