"The Tomb" possible casting

It was big news last year when Sylvester Stallone had taken the lead in the upcoming thriller "The Tomb", taking over from Arnold Schwarzenegger who was set to be taking the role. News broke today that both actors could be taking leading roles in the film.
The film, formerly set to be directed by Antoine Fuqua (Shooter, Brooklyn's Finest) tells of an expert prison designer who has to escape from the very structure he helped create. Stallone is still likely to play the lead, with Schwarzenegger picking up another key role. Rumours are circulating that Mikael Hafstrom is set to direct.