Of course, this is still speculation at this point and the team has not made a formal announcement regarding this.
Matt Maiocco of the Press Democrat had this to say in his blog, Instant 49ers:
...the team is going to wait until they see how things go Saturday night when Staley and Harris both play against the Bears' No. 1 defense. (However, I'm in agreement that Staley is the favorite at this point.)