[Zugspitze2]

Well i think that she will play a mayor role in the upcoming Movie and that she may be a final Boss or sth like this.

Spoiler for Already Release episodes, reasoning of my assumption:

Well first of all we get to know that she is the one who pretty much made Sengoku Nadeko into the snake God, then we also get to see her talking to Araragi after the happening with the darkness and you can pretty much assume that she is the mysterious darkness herself. Additionally she made one of Kaiki's Victims kill him. The Last Point is that she is not the niece of Oshino(WHO has no relatives) and since he also game Shinobu the name(with Oshino as the sirname)it is likeley to assume that oshino met Ougi in the past and sth happened between them. Suprisingly Oshino himself is absent