According to Dark Horizons, Bryan Singer said that he would be interested in directing a fourth installment to the "X-Men" franchise, if given the opportunity. The director said that he has even discussed it with 20th Century Fox already.
Singer, who spoke about the film while attending the South Korean Pusan International Film Festival, didn't state whether or not the film would be a spin off or a future installment to the three previous films. He did say, however, that the appeal for him to direct would be to work with the cast members, such as Hugh Jackman, that he worked with on the first two films.
Singer stepped back from directing the third installment of the franchise to direct "Superman Returns". Brett Ratner of "Rush Hour" fame took over on that project, while Gavin Hood directed "Wolverine".