In this talk with one of the writers at WOTC last year (chris perkins), he talks about the status of Bhaal, Myrkhul, and Bane since the Second Sundering -- they are now mortal beings who are killable because they refused to stop meddling in Faerun --- (start @ 20 min in)
https://dnd.wizards.com/articles/features/dratalk_arnieniekamp