Last week, Kotaku ran an article on Blizzard, The Past, Present, and Future of Diablo.
It has lots of interesting tidbits about Diablo's development. Basically Blizzard opted to work on Diablo IV's development instead of a second expansion of Diablo 3. The article presents that as a "bad decision". But honestly, I remember the chatter around around D3 at the time. A lot of the gaming community didn't like the direction of D3, and Reaper of Souls didn't really change that.
It's a bit of revisionist history to say the community loves Reaper of Souls. Yes, it fixed a lot of problems in the base D3, mostly by closing the auction houses and adding the Crusader. But by and large, the people who liked D3 before Reaper liked it afterwards, and the people who didn't like D3 before Reaper still didn't like it afterwards.
So I think the decision to move on from D3 is defensible. As a fan of Diablo 3, it's not what I would have preferred, but it is reasonable.
There are is some interesting information about Diablo IV's development. The first idea, Project Hades, was a Dark Souls variant. Over-the-shoulder perspective. I think it would have failed miserably as Diablo IV. Blizzard ended up cancelling this one too.
The current project is codenamed Fenris. It's a more traditional Diablo, going back to more D2 aesthetic rather than D3. But it's a few years out, so Blizzard isn't saying anything about it publicly.
The most interesting part of the article, though, is the fact that the push for mobiles games is coming from Blizzard senior developers, not the business side. It seems to be a reaction to the very long development cycles for PC games.
An AAA PC game apparently takes a decade to build, and a mobile game takes 1 to 2 years. I can totally see devs wanting to shepard a project from inception to fruition in two years, rather than spend ten years of your life on single game, with a high possibility of seeing it cancelled halfway through. Make five different games rather than one.
The interesting underlying question is why AAA development is taking so long. Is it the art requirements? Is it the game engine that new properties require? Is it just that content creation for expected amount of playtime takes so long? Does iterative development, which Blizzard is famous for, waste too many resources, even if it produces a better game in the end?
We'll see what answers Blizzard comes up with. To be honest, this makes me more interested in Diablo Immortal, and seeing what Blizzard's new team comes up with, even if it is on mobile.