Gaiman’s status as showrunner was confirmed by this photo from the official Terry Pratchett Twitter account (Pratchett passed away in 2015):
So. #GoodOmens is happening then. pic.twitter.com/V0oy7VDXdE
— Terry Pratchett (@terryandrob) September 13, 2017
And the below blurry photo might be unblurred soon:
Some of the Good Omens casting is getting announced, now that readthrough is over. So blurred photos like this might be unblurred. pic.twitter.com/5wHvzUN9yt
— Neil Gaiman (@neilhimself) September 14, 2017
But in a subsequent tweet Gaiman revealed who was fuzzed out: “Emerald City” star Adria Arjona, who will play Anathema Device; Nina Sosanya, playing Sister Mary Loquacious; Ned Dennehy, playing the demon Hastur; and Ariyon Bakare as the demon Ligur.