Thus, anyone who had the unit in their save files would still be able to keep it, but it would quietly "encourage" people to stop getting it.
Namely, I would like to split the Elvish Sorceress off into a separate
line, so that over the next few releases people are not
hiring/acquiring the thing in campaigns.
I would not change the id of the unit, I would really just sever the
leveling connection to it from the shaman.