Wow just wow.
None of what you said about WW is relevant. If JL is supposedly not responsible for its own failure brought down by brand "damage" that would equally have taken down other DC films.
JL is also not a sequel to BvS. Its a team up with some of the characters. SS also has Flash and Batman and an end credits teaser for JL. WW quite obviously is a central character in BvS and JL. And starring Batman and Superman? Superman was literally left out of all advertising.
JL flopped for a variety of reasons. Unlike what you Snyder haters delude yourselves it's not because BvS or some imaginary "damage" to the brand. And when Aquaman comes out and does just fine that will prove my point.
As far as JL flopping its several factors. Stupidly opening two weeks after a strong Thor film. Other films like Wonder or Coco overperforming. Bad press and constant negativity. Everything from Batman leaving to the supposed hiding of reviews to uncertainty around future films. Why invest in a franchise that may be going nowhere. There were accusations of sexist portrayals of the Amazons, WW ass shots, sex jokes. Poor advertising not showing Superman and building little awareness much less excitement. WB rushing the film leading to poor CGI. Then of course bad reviews and later bad word of mouth. Like it or not there was backlash from the core fanbase who wanted Snyders vision.
Additionally there are some factors others don't mention. Thinking Justice League is some known quantity is absurd. That name alone as a title doesn't spell out what the film is. This is why Batman v Superman opened higher. Also expecting some magic billion or more is absurd. Marvel created a strategy that worked. Use a series of solo films to build an audience and then team them up. There was no build up to Justice League in a similar way. At the least we needed a Batman film. Don't forget by these absurd standards Batman Begins flopped. It was TDK where Nolans work paid off.
There are a ton of mistakes made that led to JL, but it's not some imaginary "damage" to the brand. A narrative crafted exclusively to pin the blame on Snyder for a film that was creatively no longer his.
DC will be fine and as long as they correct some of these mistakes going forward the next team up could be set up as an event film that makes huge box office.