I can see them adding it on an early or mid-tier raid boss; perhaps one that is optional.
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Honestly outside the joke, I think Orc Shadowmoon Necrolytes are closer to shadow priests than anything else.
And I do wonder if the Mag'har might have a few holy priests and paladins who learned the ways of the Light but still sided with the orcs in the war. Probably not given how Geyarah reacts but it could explain the inevitable orc paladins given we've been told they will slowly implement all races all classes.