In a nutshell: The editor behind this new claim has a solid track record, having correctly predicted Diablo 4, Shadowlands and Overwatch 2 announcements before they were officially revealed. Vicarious Visions also worked on the PC port of Destiny 2 and Crash Bandicoot N. Sane Trilogy, so there's that.
When Blizzard Entertainment revealed in the summer of 2018 that it was working on multiple Diablo projects, fans of the franchise naturally speculated about what those games might be. It wouldn't be long before we learned of a Diablo III collection destined for the Nintendo Switch. At BlizzCon that year, Blizzard shared information about a new Diablo mobile game.
Fans were upset, and understandably so. What everyone really wanted from BlizzCon 2018 was Diablo IV, not a mobile spin-off. That would come, albeit a year later at the 2019 convention.
Hope for an official Diablo II remaster remained high yet were seemingly dashed later that year when the game's creators revealed that key elements of the Diablo 2 source code had been lost years ago during the final stages of development.
"It would make it very difficult for Blizzard to do a Diablo 2 remaster because all the assets we used are pretty much gone," said Erich Schaefer. "They'd have to make them from scratch," he added.
According to at least one source, Blizzard is apparently moving ahead with the project regardless.
French site Actugaming (per PC Gamer) claims a subsidiary of Activision called Vicarious Visions is working on a remaster that'll launch in the fourth quarter of this year called Diablo 2 Resurrected. The game could be delayed slightly due to current world events, the site warns, but seems confident enough in its sources to at least report on it.