There's now evidence to suggest that the rumoured Assassin's Creed 4: Black Flag remake is in active development. Word of the supposed project spread last summer, when the title was said to be in its very early stages at Ubisoft Singapore — the studio behind Skull and Bones. However, relatively fresh updates on a lead artist's LinkedIn profile (as spotted by @Jorraptor) seemingly confirm that a chunk of the team had been moved over to an "Unannounced Project" from September 2023 onwards.
Of course, given previous reports from reliable sources, it's fair to assume that this currently unnamed game is the Black Flag revival. The timeline means that we might see something of the project later this year, but we suppose that depends on the remake's overall scope.