If anyone ever wonders 'how powerful' is Lilith. I'm just happy that they decided to go with Lilith, since it's the last 'threat' that can be made into the main villain and still pose enough danger to any would-be heroes to go against the forces of Hell. I would hate it, but I'm prepared for something like that to happen (or maybe for much later on in D4's expansion pack, we'll see in about 10 years from now). I do imagine that in one way or another at least Diablo himself will make a return. However, of course, the game is still called 'Diablo'. They would have had to rework a lot of the D3's late story lore from the campaign in order to seemingly just bring back even just one of the Evils into form without making it look way too contrived with nonsensical plot armor. It just so happens that Mephisto was the only one of all the Prime and Lesser Evils to have offsprings with the short-lived exception of Diablo (with her 'daughter', Leah) in D3. It was intelligent on their part to go on with the story's continuity after D3 with Lilith, really. Additionally, Linarian (also known as Rathma, the pale-skinned Priest man we see in the trailer welcoming Lilith) happens to be a first-generation Nephalem, therefore the 'son' of Lilith (and Inarius) also he's a Necromancer (which itself is just another term for 'Priests of Rathma'). Also, she has a brother, Lucion, who we never saw in a Diablo game before he too I believe will play a part in the game (at least I hope so).

I'm guessing that she'll try to 'reform' Sanctuary fitting her desires. I'm also expecting Inarius to play a role in the story at some point (Inarius fell in love with Lilith after he was captured by her during the Eternal Conflict). We had very little lore to go with in D3 about Lilith, but it's enough to know that she created Sanctuary and now that she's been summoned on it with her physical form things will start to shape up.

I'm happy they decided to go with Lilith, instead of once more bringing back Prime and/or Lesser Evils. Yeah, probably a mid next-gen title (2022 at the earliest, probably more around 2023 or 24 for its release).

Diablo 4 cinematic who is the priest