I have a lot of respect for BZP's news staff, especially when they make publicly known a huge influx of movie info, but in all honesty...
However, consider this-- how is a movie going to work in an "extended ending" where the traitor exacts revenge on his foes? That would require a MAJOR cliffhanger ending, since his "enemies" would probably be those characters we regard as "the good guys". And there's no way that with an ending that critical to the story, it would get shoved aside to appear only in an "extended version".
As I see it, it could very easily be Metus exacting his revenge either on the traitor (which would imply a traitor that Metus either trained or trusted, possibly Strakk) or some Skrall who wrongs him during the movie plot (which is on the other end of the spectrum, as an ending that wouldn't be dramatic enough to be advertised as anything other than a "deleted scene").
...but these are just my personal thoughts. Any you'd like to share?