Just a week ago, Blizzard announced a brand new franchise they currently are developing, which will be some kind of survival AAA title with fantasy themes made for PC and console (which likely means Xbox as Microsoft is set to own Blizzard). Considering the fact that this was the first time we officially heard about this game, and the fact that Blizzard usually takes their time developing games, we assumed it was very far off.
But as it turns out, this isn't necessarily true. The Project Lead Craig Amai writes this on Twitter with a link to the Blizzard announcement of the new game:
"Once upon a time this dream project was humble pitch deck on my desktop. Now it's a team full of caring and passionate people sharing a vision I couldn't be prouder to be part of."
If you check his LinkedIn profile, you'll find out that he has worked on this yet to be named game since July 2017. This means it has been in development in some capacity for almost five years already. While different stages of pre-production certainly isn't the same thing as full production, it hopefully means that we won't have to wait for an unreasonable amount of time to find out more about this mysterious project.
Thanks GamingBolt