The LA Times has an article up that nicely frames the issues resulting in the delayed release of 47 Ronin to December 25, 2013.
The problems surrounding the film are several. There were conflicts with the studio and the first time director, Carl Rinsch . Apparently the studio has had a tight reign on him for the post-production work and all of the reshoot planning according to an inside source.
The reshoots, which are now scheduled for late August and early September, have also been plagued on several fronts. The studio was hoping to do them earlier but Keanu Reeves has been tied up filming Man of Tai Chi and the locations in Budapest were not available and there were scheduling conflicts at the London location due to the Olympics.
An inside source has said that none of the films visual effect work has begun yet making it impossible to have a trailer for a promotion role out for February 8, 2012. With the Christmas release date, there should be plenty of time to get the film finished and properly promoted for the holiday season release.
The entire article can be read at the link above.