You're right, Gunn isn't contradicting anything, except, when coupled with everything else that fans nitpick at, such as the majority of the actors having not heard a peep about the project until recently, it is not like fans have nothing to be worried about.
Given the fact that a justice League movie was almost filming during the dark knights release, only for the plug to be pulled at zero hour, Batgirl being cancelled, or the debacle of a complete reshot movie for the 2017 Justice League, WB has a history as a studio of some out there decisions.
The Batman was successful, the penguin even more so, that I do think it's going to happen. The question to me, has and will always be, do they connect this series to the main DCU or not. Zaslav is looking to IP's for it's film slate going forward, there is no doubt in my mind they want a unified approach.