Although the scene doesn't show Tyrael's personal involvement, his design of the Horadrim and Diablo 4 Gold influence with the various Paladins of Sanctuary indicates that he's involved. Dark and light clash on the battlefield, while the now-mortal Tyrael lies somewhere between.
It is highly likely that his presence will be felt through these intermediaries until events cause him to act. Tyrael is still feeling the repercussions of the destruction of his Worldstone at the end in Diablo 2. The mystical artifact shielded Sanctuary from Heaven and Hell, and he now serves as the protector of the land in its stead. Tyrael is unlikely to lead any further charges into Hell or take his fight any further that The Pandemonium Fortress, where he might provide advice like Deckard Cain for those who will stay and listen.
Five Diablo playable classes have been announced so far each of which alternatives to the earlier games. Given each installment so far has brought something new to the table and exciting, maybe Tyrael could become an element of the battle, balancing the sides by offering players the ability to summon angelic or demon powers in exchange for duties to Sanctuary. This type of game mechanic is likely to be similar to the multi-tree progression that was already confirmed for the series.
It is unlikely that Blizzard plans to make Angels or Demons into classes as the franchise focuses on the people who are caught between the two. But as a mortal caught between Heaven and Hell, Tyrael sits in a unique position in all of Diablo story. He is more likely to be an equalizer in the tale, perhaps even as a voice of reason rather than a side-lined player as his former self. Even when forced to take positions, Tyrael understands what is important to mortals and that's why he'll most likely take part in the events in Diablo 4.
Blizzard's strategy for speccing your character's abilities in Diablo 4 is a blend of the studio's approach to Diablo 2 and Diablo 3. As executive producer and director of the Diablo franchise Rod Fergusson put it, "Diablo 2 felt like you were locking in; you were able to change your character at least once per difficulty. With D3, you kind of changed your look like you would change your clothes. Everything was gear-based as opposed to skill-based."Fergusson added, "I think the fact that we have skills on the equipment [in Diablo 4] is really nice for experimentation -- as a sorceress I [might] get Blizzard [on a pair of boots] three levels before I should and buy cheap Diablo IV Gold I can try Blizzard to see if I actually want it."
