Blizzard refuses to say what Diablo 4's new class will be, but its own leak gives us some clues

pcgamer.com:

Blizzard refuses to say what new class is coming to Diablo 4 when its first expansion, Vessel of Hatred, launches late next year. But datamined text from a leaked build of the game makes it pretty clear what it will be.

Officially, Vessel of Hatred will continue the story in Diablo 4's campaign, and will have you chasing down demons in Nahantu, a region last seen in Diablo 2 under a different name: Torajan. There you'll find the new class, which, as Blizzard says, has never been seen before in the series.

The new class won't be a Witch Doctor or a Paladin, Diablo 4 associate game director Brent Gibson told GamesRadar at BlizzCon. The team wanted to go with a class that nobody has played before in a Diablo game.

That class has to be the Spiritborn. Blizzard hasn't acknowledged the mistake it made in early October when an internal testing version of the game was updated and made briefly available to former beta testers for Diablo 4's launch. The few who managed to download it found text in the files that points to the Spiritborn class and its abilities, along with other hints at upcoming features coming to the game.

Days before BlizzCon, an MMO-Champion forum user posted a leak derived from that same text dump. Although Blizzard's official descriptions of Vessel of Hatred's jungle setting are more vague than the post, the two largely match, suggesting the leaked build of the game was in fact an early version of the expansion. Wowhead even found that an item named the Ivory Horn of Torajan was renamed to the Ivory Horn of Nahantu in the live version of Diablo 4 last month.

The leaked build doesn't paint a full picture of the Spiritborn class, but here's what we can assume from the text: 

My money's on the Spiritborn