This may be the first iPhone event where the iPhone isn't the star of the show! I've been saying for years that an App Store-equipped Apple TV could be a game-changer, and could put Sony and Microsoft on their toes. Now it might come to pass.
As for the 6s/6s+, it's high time they concentrated on specs. Make the processor at least quad-core (octa-core preferably but I doubt it), bump the RAM up to 2GB, and get the camera up to at least 12, preferably 16 megapixels.
Meanwhile, Force Touch could be revolutionary, and I'm already anticipating Darth Vader and Chewbacca getting dragged out on stage to demonstrate it (since Disney and Apple are besties, after all).
Oh, and a Taylor Swift appearance. Because why the fuck not.