Back in July, a Blizzard employee unveiled most of the details presented at BlizzCon, but the Reddit post was dismissed as pure speculation. Nevertheless, the details are spot on for the most part, and there is some info on aspects that haven't been touched in the BlizzCon presentations, like the full class roster, planned classes, next gen console support and closed beta planned date.
https://www.notebookcheck.net/Unconfirmed-Diablo-IV-details-spotted-in-4-month-old-leak-full-class-roster-revealed.442665.0.html