The latest Diablo IV Gold cinematic trailer from Blizzard includes Inarius looking down Lilith as well as armies at both of their backs. While the scene does not mention Tyrael's direct involvement, his involvement in the creation of Horadrim and his involvement with the Paladins of Sanctuary ensures that he's involved. Light and dark clash across the field, and the now-mortal Tyrael lies somewhere between.
It is possible that his presence will be experienced through these intermediaries unless events take his hands. Tyrael continues to feel the consequences of destroying his Worldstone at the end in Diablo 2. The mystical artifact safeguarded Sanctuary from Heaven and Hell and now is the protector of the land in its stead. Tyrael seems unlikely to lead any further actions into Hell or take his fight any further then to the Pandemonium Fortress, where he might offer advice similar to Deckard Cain for those who stay and listen.
Five Diablo playable classes have been revealed so far and all are variants of earlier games. With each of the games that has been released so far has introduced something new maybe Tyrael might become an active participant in the fight in the battle, helping to balance the sides by giving players the chance to acquire angelic or demon-like powers , in exchange for responsibilities to Sanctuary. This sort of mechanism could be a natural progression from the multi-tree progression that was already made public for the series.
It is unlikely that Blizzard plans to make Angels and Demons into classes, given that the franchise centers those in the middle of their journey. But as the mortal truly caught between Heaven and Hell Tyrael is in a unique position in the entire Diablo story. He'll likely to be a balancing act in the story, maybe even as a voice of reason instead of taking sides like he did in the past. When he's not forced to pick sides, Tyrael is now aware of the true value of the mortals, and that is why he'll most likely participate in the events of buy cheap Diablo IV Gold .