WB/DC's problem is rebootitis taken to absurd extremes. If a film doesn't gross a billion, reboot. If a film doesn't test as well as a film which grossed a billion, reboot. If a producer watches a daily and doesn't think it looks like something that might gross a billion, reboot. If it's Tuesday, reboot. Executive meddling in hope of guaranteeing that everything released sets records has crippled them. At this point, when they do manage to push something out the door, we expect them to abandon it, and we don't develop an attachment, or even interest, because we already know there's nothing coming in the future. We don't trust them to deliver on the promise inherent in superhero films, the promise of continuance, of sequels. They'll either reboot or throw it away, so no-one cares any more. James Gunn coming on board and cancelling even more projects, while green-lighting B- and C-lister properties... that probably isn't going to help as much as they imagined it would.
Marvel built up so much hype and excitement with their original Avengers line-up that moving on to different characters was what hit them the hardest. I've read various complaints about what they've done after Phase Three, but as I've only seen Black Widow, Shang-Chi and No Way Home, I'm not in a position to agree or disagree with them. But we all spent over a decade watching the central characters and seeing their stories play out, and when those characters were removed, it left a big hole in the MCU. We can't blame Marvel for that, they couldn't chain the actors to the characters, or drag out their stories, indefinitely. Nor were the actors at fault, they have lives and interests outside of the MCU. But those characters and the actors playing them were what kept people going back for more, and without them, Marvel's fighting an uphill battle to recreate what they built in Phases One through Three.
I don't envision Co*'s return to the light having any impact on either of them. It doesn't touch on the problems affecting those companies in any way. It's not going to make people believe DC will get off the treadmill and start moving again, or insert retired characters into Marvel's new offerings.