Aye,
so after I’ve got spoilered in the forums and from what I’ve read, seen and heard, I definitely want Lilith to return in some form or way (just like Inarius) and I’d like to be able to side with her. Latter thing might need some work to properly integrate but I believe Lilith has some great potential story-wise and if Blizzard wants to support this game for years to come, it’d be a shame for Lilith to just be a historical sidenote 
They have 2 confirmed expansions already so probably get your wish sooner than later.
In my opinion, Lilith was just used to introduce Mephisto back the Diablo game. Nobody will miss Inarius. For me he is a douchebag and did deserve to die like he did in this story.
We still missing Diablo himself, so they need to work on the story hard, because otherwise the game name is just wrong.
We need to see vengeful demon Inarius that’s consumed with hatred and intent on getting revenge on the high heavens for abandoning him… again. Maybe he’ll be the one to bring Diablo and Baal into Sanctuary again.
I could see the protagonist somewhat failing to stop them and being in need to somehow revive and empowering Lilith ^^ After that maybe she seeks redemption or maybe because after we revive her for some sort of thanks or something like that. After all it’d be humans that brought her back again. So she truly becomes mother of Sanctuario.