As far as we currently know, the Warriors of Darkness (that is, Arbert & company) are properly dead and gone. At the close of 3.4, when they return to the First with Minfilia, both they and Alphinaud seem to be under the impression that the WoDs returning to the First in their current state would mean their souls would finally be compelled to return to the Lifestream.

Quote Originally Posted by Alphinaud
I cannot help but wonder what awaits those wayward souls. If they gave their lives in order to travel to the Source, then in returning to the First, would they not...?

...But mayhap that was their wish.
Now this does seem a little strange, because if Ascians are, as is strongly hinted, former mortals who have transcended their bodies through the Echo and gained great power, why is it that they can continue to exist in their own home worlds, while the Warriors of Darkness will cease to be if they return to theirs? Perhaps Shadowbringers will clear this up. Either way, the WoDs' departure in 3.4 certainly carries a great air of finality.