Diablo 4 is currently in an internal testing phase and its development is progressing well, according to Blizzard’s financial report, suggesting that its release should not be too far away.
References to Diablo 4 are pretty tight, but the fact that it’s currently in the internal testing phase might suggest something about the state of play, having probably come to a good point with the game being actually playable and probably with a good amount of content ready.
It is difficult to make predictions about such a hermetic communication, of course, but if you look at the path of Diablo 3, we notice how the communication on the game entered the internal testing phase about a year before its release on the market: the information in question emerged in May 2011, with the game then released in May 2012.
Obviously, this is only a vague trace, but it could be indicative information on the progress of work on Diablo 4, which was announced back in 2019 but has seen a decidedly long development. In the meantime, these days we have received various information about Diablo Immortal such as the release date and trailer, the announcement of the PC version and also the system requirements for the latter.