Catalan parliamentary elections
Regional president Carles Puigdemont can call an election at his discretion. If he did so now, he might capitalise on Catalans' anger at the referendum clampdown and boost the pro-independence parties' thin majority in the regional parliament. That would strengthen their hand in the drive for secession.
General election
Prime minister Mariano Rajoy might call a national vote, sensing that his tough stance on the Catalan crisis could boost his electoral support across the rest of Spain. However, such a bold move would be out of character.
Resignation
Rajoy’s parliamentary support is fragile and his handling of the Catalan referendum has already alienated the moderate Basque Nationalist Party (PNV). With the Socialists also unhappy at recent events, congress is looking an increasingly hostile place for him.
Negotiations
Perhaps the least likely development: Rajoy and Puigdemont finally engage in a meaningful dialogue, possibly with outside mediation. While discussing a referendum would be out of the question for Rajoy, devolving more powers to Catalonia would be less painful. But would the independence movement accept that?
Independence
Under increasing pressure from the more strident separatist voices in the secessionist movement, Puigdemont fronts a unilateral declaration of independence by the Catalan parliament.