Board Thread:Spoilers!/@comment-6175354-20140126015900/@comment-5655661-20140202000136

Since Eva is going to appear in the same episode, I'm starting to think that WWoW is actually Queen Eva's sister (who may very well be Good Witch of the North since she is a princess from northern kingdom). Cora was probably involved in WWoW's "Evil isn't born it's made" story, she also killed her sister and Cora's daughter ruined her niece's life. Since Cora is dead, WWoW will seek her revenge against Regina.

The other possibility - what if Wicked Witch of the West is Leopold and Eva's firstborn daughter whom Cora banished to Oz?