My prediction for the Harry Potter series ending:
Harry, Hermione, Ron, and Ginny are sitting at Hogwart's Main Dining Hall eating a meal. People and ghosts and whatnot are coming and going around them, in and out of the room, passing through walls, etc. The four are discussing random things; just another day at Hogwarts.
But you KNOW something is coming; it's the end of the last chapter. Will Harry live or die? You turn the page and...
Was it a printing error? No, just a lame-ass ending. Or a brilliant ending. Whatever.