The project was previously being overseen by Steven Soderbergh, potentially as his final movie before retirement, with George Clooney set to star in the part that Cruise just vacated. Clooney's back injury, sustained during the filming of "Syriana," kept him from doing such a physical role, and after that Soderbergh had trouble finding a suitable replacement that the studio was happy with, so he quietly left the project.
It picked up steam again when Ritchie and his "Sherlock Holmes" producing partner Lionel Wigram were handed the film. Cruise would have played Napoleon Solo, a character originated in the series by Robert Vaughn. Hammer will still play Illya Kuryakin, a Russian agent. Both spies report to the United Network Command for Law Enforcement, a sort of utopian international spy organization dreamed up at the height of the Cold War.
Cruise will next be seen in Doug Liman's manga adaptation "All You Need Is Kill" (best title for anything ever), next summer. He supposedly left the "U.N.C.L.E." project so he could focus on the fifth "Mission: Impossible," which is currently being written by "Iron Man 3" co-writer Drew Pearce, with "Jack Reacher" director Christopher McQuarrie loosely attached to helm. Based on reports, Cruise will spend the rest of the year getting "Mission: Impossible 5" up and running, which will once again be produced by J.J. Abrams and his Bad Robot team.
The search is now on for a replacement for Cruise, with production on "The Man from U.N.C.L.E." still set to commence this fall.