Today's Embers of Neltharion PTR build added a new Neltharion-themed plate helm and shoulders. While we don't know for certain, looking at the data, they seem to be raid drops in the new raid, Aberrus, similar to Garrosh shoulders in Siege of Orgrimmar.
The helm and shoulders closely resemble the gear used by the new Neltharion model found in 10.1. It seems that Blizzard has been planning on adding these appearances for a long time, as there are icons related to those items in the game's data since 10.0 alpha:
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