Hey, maul also fell down a bottomless pit. And he was CUT IN HALF. Oh, and Luke also fell down a bottomless pit.
So I wouldn't be surprised at all if he returned. Wouldn't mind it though, Malgus is a pretty awesome character.
Do not forget boba fett fell into sarlacc pit. Yet he lived. So just because you fall in a pit the the star wars universe does not mean you will die.