Sherlock Holmes: A Game of Shadows, but there's an interesting rumor floating around. Could Guy Ritchie take the reigns from Zack Snyder on a 300 sequel? The internet says so, so it must be true.
If the rumors are true and Ritchie is to take over the sequel, there has to be other reasons. Say perhaps, SCHEDULING! Shocking, scheduling difficulties is too boring a reason for a director to take over a film from another director; so we all make stuff up to compensate.
My honest opinion is that Warner Brothers wants to get this project moving and so they're probably shopping around, nothing more. With Snyder starting up Superman and Ritchie wrapping up Holmes... it makes sense. I would be happy with Ritchie, but am going to hope for a back to back homerun with Snyder.