I know what you're talking about. I have only seen the two Batman movies directed by Tim Burton (Batman and Batman Returns) as well as The Dark Knight, but I was a huge fan of the 90's Batman cartoon series. So I took all the "jump the shark" talk about Batman after "Batman & Robin" crashed and burned.
So I know what Bats is talking about concerning those who say that MLP:FiM jumped the shark when Twilight Sparkle became an Alicorn princess at the end of Season 3. I personally think that this will open up new possibilities for both Twilight and her friends. I believe that Twilight will (in Season 4) remain (her wings and title notwithstanding) the same adorkable egghead we know and love.
As for those who are grousing over Equestria Girls, keep in mind that ever since the fandom began there have been fanfictions, fanart, fan memes, etc. that have portrayed the Mane 6, The Cutie Mark Crusaders, secondary ponies (like Derpy Hooves) and even the Alicorn Sisters (Celestia and Luna) as humans. And now, since the animators produced a movie showing Twilight and company as humans it's a jump the shark moment? I think not.
Let's just see what happens when Season 4 starts, keep calm and brony on.