No, nothing is ever certain until I'm holding the book in my hands. But with an official announcement I at least have word from the actual publisher/creator instead of something from second or third hand sources I can't verify for myself.
Rumors and unofficial news get some consideration but I take none of it seriously, and official announcements only a little more seriously since even "official" plans change at the drop of a hat. Especially when it comes to DC, who pivot more than a NBA point guard on meth.