As always the Battle Bunnies are never satisfied. We want to know what book is next, and unfortunately we have no idea. It was meant to be Inferno, but it apparently could be any of them. There will be a lot of new models and unit types on Prospero (Custodes, Sisters and Army), so maybe it would make sense to put this book back a touch to allow them to drip feed it to us in a Calth book before Prospero. Apparently there will be some incredible surprises at the Horus Heresy Weekender, so I fully expect FW to have more aces up their sleeves.