As far as we know ADB's Master of Mankind is just on hold while he works on the Black Legion stuff so that should still come out eventually.
Chris has been all quiet on the Black library front for a while but seeing as the Age of Sigmar novella has been written by him I assume he is still writing something 40k related and a Scars sequel would make sense.
The only one you highlighted that seems unlikely is Dan's as he has been working on so many other projects everywhere else him finding time to write HH, Warmaster, Penitent and the mysterious I am Slaughter alongside his comic, game, film and other novel work. but from what I heard he was pretty passionate about the Dreadwing project so it may see the light of day... eventually. With Angels of Caliban setting up the events with Corswain and Caliban's fall just on the horizon, having Dreadwing explain how the Lion got out of Ultramar and to Caliban after Angels of Caliban makes sense. So Dreadwing could just have been pushed back for that reason.
The one I'm most curious about is Rob Saunders Martian stuff. Wasn't cybernetica announced years ago then... poof! Nothing. Sounds like the most likely one to have been cancelled/ not happening.
And on a similar point, what happened to James Swallow? Do we know if he’s doing anything Heresy related since the last Garro story? I know Death Guard was floating around a while back but has there been any news on that front?