Speaking in a recent interview, Blizzard's senior producer Pete Stilwell said that there are no plans for Warcraft 4 at the moment, seeing as how the company currently have their hands full with all the work around Warcraft 3: Reforged.
"I wouldn't rule anything out but we don't have any plans around [Warcraft 4] at this point", Stilwell told Gamespot. Stilwell pointed out that Warcraft 3: Reforged is their "priority first and foremost" and getting it right is proving a handful.
Blizzard are apparently reworking Warcraft 3 to the core, throwing in 4K support, animation and character remodelling and a bunch more. Getting Warcraft 3: Reforged up to scratch goes beyond the technical aspects though and Blizzard's design team is currently working on making the game "more accessible for today's players". In translation, it means tweaking the campaign missions so that they're a bit easier.
As for the rest of the RTS experience, Warcraft 3 will remain intact, since the game has been around for 15 years, just like its community. Its longevity is further boosted by World of Warcraft, which has greatly expanded the RTS franchise's lore.
Of course, Blizzard have their hands full elsewhere too, especially since Diablo: Immortal didn't quite meet the sort of enthusiastic response the company would've hoped for. Their response hasn't fared that great either because once you've brushed away all the it's-a-brand-new-game PR talk, all that's left is that Blizzard really, like really, want a piece of the Eastern mobile gaming pie.
Admittedly, Blizzard expected a slight backlash but what they faced surely didn't sound slight in the slightest. It even led to criticism by Mark Kern, Diablo 2 and Starcraft's producer, who said, " I would have had a line of devs outside my door telling me this was a bad move".
Kern also pointed out that there's nothing wrong with mobile Diablo, quite the contrary, but the way Blizzard went about the whole thing definitely doesn't inspire confidence. He thinks they should apologise by rolling out a trailer for a proper Diablo and we can't say we don't agree with the man.
You can find Stilwell's statement to Gamespot here.