I agree that wb needs to be more methodical with the other titles. Batman is a terrific character and is full of potential, even now for movies and comics. However, when it comes to most other movies they’ve shoved through to “combat” the MCU, they just keep poisoning the well. Several people have argued that DC character (with exception of the bat) are not translatable to the silver screen. I call bull. No matter how terrible its former iteration, any source material (book, comic, weird story you read) can be turned into a good or even great movie.
Wonder woman proved DC has more than one character that can produce results. The lesson there? Stop giving projects that has a following to whoever name of director you draw from a hat. Give it to someone who a) is competent b) give a damn about the source material and c) give a crap whether or not the movie is good.
As far as I see BvS and JL, yes they are failures. Spectacular ones. If you can learn from the plethora of mistakes made, listening to the complaint from the cast and crew, watching what caused the disjointed schism, you can easily make a better DCEU. With or without the old cast. The actors and actresses are solid. But get a director who cares. Even the best actor can’t fix a crap script and chaotic production where you are told a thousand answers for the same question (this is what happened to batfleck when he asked" what kind of Batman am I?")
As far as other characters, that route can work to slowly fix things, but it needs to be done right, methodical, not shoved through and pray it doesn’t suck at the box office.
My thoughts? The supersons comic series would be great for the whole family
Reapproach green lantern, but use a different character. John Stewart is a solid choice. Maybe add Kyle Gardner if you want some comedy/action.
Red Hood and the Outlaws could be a dark thriller ( but I am a huge fan so just ignore me on that) or once they finish the current Red Hood, outlaw story, start with that, work backwards.