As amazing as the current season of “ American Horror Story ” has been so far, with its extraordinary physical specimens, murderous intrigues, and gratuitous tighty-whitey workouts by its petulant villain, the whole thing has also been imbued with a certain creeping melancholy: the further we get into the fantastic plot of “Freak Show,” the closer we come to Jessica Lange’s last appearance as the series’ grande dame . It’s been widely reported that this will be La Lange’s last season on the show, without so much as a whisper of news that she might reconsider and stay. And with the end of “Freak Show” already looming, it’s time to stop pussyfooting around reality: Jessica Lange CANNOT be finished with “American Horror Story” yet. We won’t allow it! And here’s why. 1. She’s clearly not done doing accents. Between this season’s sultry German growl and the gritty Boston patois of “American Horror Story: Asylum,” Jessica Lange is clearly not done displaying her talent for di...