I have a feeling that inarius will be rebirthed as a new incarnation of hatred that we potentially saw in those flashes after the credits. Between him and Lilith he was the one who had true hatred for sanctuary whereas Lilith only had (maybe) love of some sort and only seemed to hate the eternal conflict. Also in the prophecy Lilith is also explained to be pierced by a spear of light well, you can take that very literally as the spear inarius held or (as he belonged in hell and the spear was held with greed/hatred more of a darkness spear if you will) she is to be reincarnated in heaven as an archangel of some sort. Just my thoughts I think it would have very cool implications if they swapped places in the eternal conflict.
Would be interesting to see them switch places, but doubt Lilith could be reborn as a Angel. Everything she did to Sanctuary during D4 campaign was pretty deplorable. Meanwhile, Inarius may physically be an Angel but his motivations no longer align, and he acts more like a demon - motivated purely by self interest.
I think the prophecy actually hinted towards this and it’s a popular interpretation:
At the end, Inarius is operating solely off hatred. He wants to destroy Sanctuary just to get back into Heaven, and Lilith points out they don’t care and do not answer him. He then shows anger towards Heaven, asking why the other angles still forsake him. Lilith then takes the spear (from her lower abdomen) and plunges it through his chest. The use of Hatred as a proper noun is just a red herring that Inarius fell for, assuming it referred to the daughter of Hatred.