Almost certainly not. there is apparently text in some book about Slannesh being captured and imprisoned (ala Isha in 40K) and very little mention otherwise.
GW almost certainly wants to phase out Slaanesh to make their brand more child friendly. Having a deity of sex, drugs and overindulgence wouldn't go over well in some circles.
Wait, how does Slaanesh being captured work with the 40k universe?




