There weren't any rabbis in Jesus' day. The Pharisees weren't rabbis and the scribes obviously weren't (because they were scribes). The rabbis as we know them were a post-70 CE development, though they were, in many respects, apparently the spiritual descendants of the Pharisees. So it doesn't make sense to talk about rabbis being replaced by bishops - the "office" of rabbi developed at the same time as that of bishop.