It appears Diablo 4 microtransactions will be coming to the game, according to lead developer Joe Shely during a livestream that broadcasted during BlizzCon 2019 that also involved Twitch streamer Quin69. Diablo 4 was the first of two major reveals Blizzard made during the opening ceremony of this year's BlizzCon, and it's already receiving an influx of attention thanks to how heavily it plays towards Diablo 2, a game that many feel is the best the franchise has ever seen from both a gameplay and lore perspective.
Diablo 4 will need to be excellent, as Diablo 3's canceled second expansion tells the story of a predecessor that failed to live up to expectations despite finding its footing months after its initial launch troubles. It will also be competing with Diablo Immortal, the mobile game Blizzard is developing within the Diablo universe and a game that was incredibly divisive when it was revealed at BlizzCon 2018 - a moment many believed was reserved for the announcement of Diablo 4. The backlash for Immortal was at least partially informed by that expectation, but the fact remains that Diablo 4 will have great expectations set for it, especially after an upsetting year for Blizzard following its Hong Kong controversy.
That's why the topic of Diablo 4 microtransactions has already become a hotly contested one for fans - the perception remains that the business model tends to produce lesser versions of what games could have been, even if that's not exactly supported by the evidence of the last few years' worth of releases. According to Shely (via PCGamesN), however, Blizzard will in fact be implementing Diablo 4 microtransactions after all, although the company plans for them to be purely cosmetic at this time. That doesn't mean plans won't change one way or the other, between no microtransactions at all or a different model, but for now, this is what Shely stated following a prompt from Quin69 during the stream about if microtransactions or subscriptions will be featured:
"Diablo 4 will be available as a base game, and...we're going to have expansions. You also will be able to acquire cosmetics in the game."
Shely also clarified that these would be available through a shop of some kind. It's also important to note that Diablo 4 is confirmed to have expansions, plural, so it appears Blizzard is at least in the planning stages for what Diablo 3 was supposed to get regarding multiple expansions and lengthy support for the game as a whole.
If Diablo 4 microtransactions are purely cosmetic, there's probably no reason to panic for fans of the Blizzard franchise. In fact, given the general look of mobile game releases over the past year, it seems much more likely that Diablo Immortal will carry the burden of a more aggressively-slanted microtransaction business model. If that's the case, Diablo 4 microtransactions will probably be harmless - and if they're not, Blizzard will certainly hear about it from an already inflamed fanbase.
Source: PCGamesN
Diablo 4 currently has no release date.