Board Thread:Lore Discussion/@comment-72.77.73.35-20140408131341/@comment-6707115-20141014131609

A Nightingale isn't forced to go to the Evergloom after death, they're only forced contractually to defend the Entrance until Nocturnal deems their service at an end (though I think she'd be fair in this regard an it would expire after several decades like Gallus). After that they receive the special invitation to reside in the Evergloom.

Unless Nocturnal and Hircine would cooperate in a way that one's obligation to Nocturnal would be completed first, and then the werewolf spirit would take it's host to the Hunting grounds, then there would be a conflict between the two.