It was recently reported that Guy Ritchie had also signed on to direct Excalibur, aptly named after the sword of King Arthur and based on a treatment by Warren Ellis (author of comic series "Transmetropolitan" and "Planetary").
But now, according to Variety, Ritchie is reportedly working on another project with screenwriter John Hodge (Trainspotting) on a re-imagining of the legend of King Arthur, using on Sir Thomas Mallory's "Le Morte d'Arthur" as a primary source.
However, one person directing two different projects at the same studio that are basically about the same historical figure is beyond anyone's imagination. It's probably safe to say that he's going to be directing a film about King Athur nevertheless. The rest of the details seems hazy, but I'm sure they will become clear pretty soon.