While Sweeney could easily carry this story - Sami being possessed wouldn't be shocking or, even, noteworthy since many in Salem already consider her the devil....
MarDevil is the right call - she's the show's moral center in so many way.
Except for Kayla or, maybe Chloe, no other longrunning female character really fits. Jennifer or Sarah, if they were around, maybe.
Gabi, Nicole, Kate - no real difference! Abigail - she's like that half the time anyway.
It's too bad they destroyed Kristen again because if she was post-TJ - almost nun, she could team with John to save Marlena, which would've been an interesting twist and a nod to history.