Board Thread:General Discussion/@comment-27738735-20151013142838/@comment-10008368-20151013184042

I think it's either the final battle against Bill or the first of multiple episodes which will revolve around the final battle.

I also do not think Mabel to be dead.

And yes, I could imagine the twins to either stay in Gravity Falls or, which is also likely, to really say goodbye to each other, one way or another.