With the final wing of Vault of the Incarnates LFR available this week, players have discovered that the Dragonriding Proto-Drake full transformation, Renewed Proto-Drake: Embodiment of the Storm-Eater, is available from LFR as well.
This full transformation changes your Renewed Proto-Drake to look like Raszageth herself. The drop rate is unknown, but from other difficulties, it seems to be around 5 to 10%.