Yours is a great question, irondork. Unfortunately, rational, critical thinking has never been a factor in Watchtower world. This new spin on a worn-out, and baseless, concept will be handled like all other doctrines- shut up, believe it, don't question the validity of it. Questioning = lack of faith.
The identity of the "faithful slave" has always been an issue beginning with Russell.
Russell originally taught the FDS was a group of Christians.
Then it came to be accepted that Russell himself was the FDS, and he did not refute it.
This view was the official doctrine of the WT for many years after Russell's death.
At one point, the "generation" mentioned by Jesus was applied only to the remnant of the FDS.
Until recently, ALL anointed ones were considered the FDS.
Now, only the governing body is the FDS.
So, if the WT, and more specifically the faithful slave, can't identify ITSELF, and has never had a clear grasp on its own identity, how then can any JW put faith in them, as the WT demands?