If there is a Blizzard title more beloved than StarCraft or World of WarCraft, it would almost certainly be Diablo II. An action RPG that learned from the errors of the first title by keeping what made the original great and vastly improved on the foundations both mechanically and aesthetically, it's been something of a high watermark for Blizzard.
It's also about 20 years old, with one sequel already out and a new one on the way. Fans may love the original, but they've certainly asked Blizzard when a remastered version would be coming forward.
French game site Actugaming has reported developer Vicarious Visions is working on a Diablo II remaster, with a tentative release window of Q4 2020. While it's tempting to chalk this up merely as a rumor, Actugaming has a pretty good track record as "Blizzard watchers."
They've been correct previously about Diablo IV, Overwatch 2, and the Shadowlands expansion for World of WarCraft, scooping other news outlets about the titles' existence and beating the official announcements. It's a little bit better than a mere "rumor," and certainly more credible than your average forum post.
However, it's not yet confirmed, and there's always the possibility Blizzard could kill the project before making an official announcement. There are certainly some logistical reasons for doing so. A report last year from Gamespot mentioned that designers Max & Erich Schaefer and Dave Brevik lost virtually all of their art assets as well as the source code during the final stages of the development process.
While the art would almost certainly have to be done from scratch anyway, given the game's use of sprites, the source code could theoretically be obtained by decompiling the finished game. The more significant issue, however, is one of image. The last game Blizzard remastered, WarCraft 3 Reforged, received a rather hostile reception from the fans. Blizzard may not be able to afford a similar response to its other classic title.