Evidence is mounting that Dungeons & Dragons is getting ready to return to Ravenloft. Yesterday, Dungeons & Dragons released two new subclasses for public playtesting, sparking more speculation that an upcoming unannounced project will be set in the gothic horror-themed campaign setting of Ravenloft. Many fans have wondered whether a return to Ravenloft was coming after Dungeons & Dragons noted that the Vistani, a group native to Ravenloft, were being revised to address problematic parallels with stereotypes associated with the Romani people for two unannounced project. Although Dungeons & Dragons later announced a Curse of Strahd Revamped Collector's Set, there is at least one other adventure that will feature the Vistani and could have ties to Ravenloft.
Both of these new subclasses - a College of Spirits Bard and a Warlock with an Undead Patron - have potential ties to Ravenloft. The College of Spirits Bard can use a Tarokka deck as a spellcasting focus and Strahd was mentioned as a potential example of an Undead patron who can imbue a Warlock with power. This could be coincidence, of course, but the timing is very interesting given what we know about Dungeons & Dragons' other plans.
While Ravenloft is most closely associated with the region of Barovia, which is directly ruled over by the powerful vampire Strahd, there are other areas ruled by equally deadly Dark Lords. Since the Vistani have the ability to cross through the mists into these various domains of dread, it would make sense that a future Ravenloft book would more extensively feature the Vistani.
Of course, two subclasses aren't necessarily a definitive sign that a Ravenloft book is definitely coming, but there are definitely a lot of clues that seem to hint that more Ravenloft content is coming soon. The real question is whether Ravenloft will be featured on its own or if it'll appear in the long rumored multi-planar book that appears to be in Dungeons & Dragons' pipeline.