Talk:Episodes, films, and shorts/@comment-5375446-20131023211403/@comment-26973802-20131024044730

You saw what those changelings were doing to Equestria. They were flying around zapping everything in sight. She still wanted to cause destruction, just not to the ponies themselves

Wikipedia's summary for it says they "discover a new foe behind these events". So it will be a new villain, Nightmare Moon would be an "old foe"