Funnily enough, Shepherd was actually originally planned for inclusion in version 1.0, but was never implemented and all traces of it were dummied out of the client (it had an empty guildhall in the hamlet of Owl's Nest in Coerthas as well). As ARR has no references to this class remaining (Owl's Nest is no longer accessible too), then we can only assume SE has abandoned this class sadly.

Your ideas for the class are very interesting though, so hopefully SE takes note and brings it back in some way.