An emotionally naked and distraught Rachel Weisz could be a major kudos mention and in what should be an astute pen-job by Peter Morgan, we think this has the potential to cross into several demos. Bidding war should involving the likes of Focus, Searchlight and the Weinsteins is a certainty.
The Messenger was/is distinct indie fare, but Moverman's sophomore effort might fall into the "Drive" category -- accessible, larger audience films with an auteur treatment with plenty of attention to the details (look, performance, tone). The James Ellroy adapted dirty cop tale is based on true events and with a larger, more recognizable cast, and a re-pairing of Woody Harrelson and Ben Foster, there would appear to be more guarantee for the buck (award nominations, wide theatrical release).
I haven't done the box office math, but citing Guillermo del Toro's contributions as filmmaker in the genre, modern day Spanish produced horror thrillers work well - especially those that have a duel timeline and where the recognizable lead is Clive Owen speaking in his mother tongue. It might be the only film of the festival to attract a bid from the major studios, so it's unlikely that the likes of IFC Midnight or Magnet Releasing will find a bargain here as helmer Juan Carlos Fresnadillo has a proven reputation in delivering the goods.
Working against the film is the fact that it is fronted by a mostly unknown pair of young female actors (Lily Cole is not An A-lister yet), and while high school and horror are as bland and unoriginal of a match as PB&J is, we need to take into consideration that this is a helmer who gave us American Psycho and that there is a demographic out there that will assure a healthy box office return. Just prior, it'll have shown in Venice, but firm offers for NA rights should be aplenty once it shows in Toronto.
Brando delivered an Academy Award-nominated performance for his pass me the butter Euro film, if the Academy can separate the condition/exploits and ugliness of the character from the actor's performance, then this should be a golden ticket Best Actor nomination perf for Michael Fassbender.